NOTES ON THE MOVEMENT OF THE POLLINIA OF ORCHIS MASCULA.

M

R. E. MALAN, in his interesting paper in the May number of SCIENCE-GOSSIP, on the Fertilisation of Orchis mascula, replying to some remarks made by a previous correspondent, infers, if I read aright, that the form of the pollinium probably has something to do with its movement, and suggests an experiment with "a roll of moist clay."

There appears to me to be an insuperable difficulty in accepting this theory as an explanation of the movement of the pollinia. The change of position is uniformly in one direction, and this notwithstanding that a pollinium may be held in such a position as to cause the direction of movement to be against gravity.

An additional proof that the overhanging weight of the pollinium has nothing to do with its movement may be tested by a simple experiment. Remove with a pair of forceps one of the organs in question, without touching the viscid disc, or allowing it to come into contact with anything; carefully observe it under the microscope, while still held quite free ; the disc will be seen to move through a similar arc, and in the same direction as it would have caused the caudicle to sweep had the disc been attached to anything, thus showing weight and form are not factors in the sense inferred by Mr. Malan.

That the drying of the viscid disc is the cause of the movement there can, I presume, be little doubt; the following experiments were made with the view of satisfying myself on this point. Selecting properly matured flowers, I removed a pollinium with a pair of forceps as before described. I immersed the basal portion in glycerine, and fixed it steadily under the microscope; after many hours' observation no visible movement of parts had taken place. Proceeding in the same way with water, I found the function, though arrested for a time, was afterwards performed when the water had evaporated; substituting benzine there was little, if any, delay in the movement as compared with a pollinium in its natural condition.

Immersing a pollinium in glycerine diluted with water on a slip of glass, a very curious phenomenon was observed. Tiny viscid globules and vermicular threads of same were ejected from the cells of the disc with some energy, resembling a miniature bombardment of particles, the general appearance being similar to the action of evaporating spirit when viewed under the microscope. A globule or thread after being emitted would frequently remain station: ary for a second or two; it would then dart off with a rapid motion, as though propelled by an explosive force operating in the region of the disc.

The action was the same when water only was used.

In both cases I did not observe any subsequent movement in the parts of the pollinium. Substituting

benzine, the emission was exceedingly feeble in some cases, in others I altogether failed to detect it, while on evaporation taking place the natural movement again set in.

With pure glycerine there was no emission, the disc became quite transparent in a very short time, but on adding a little water the action instantly commenced, the globules being ejected as before described.

The movement of the pollinia may to some extent, if not entirely, be due to the chemical qualities of the contents of the cells of the disc; the cause of movement is undoubtedly due to the rapid contraction of the cellular tissue caused by drying. The speedy evaporation may be induced by the contents of the cells being of a volatile character, as indicated by the experiment; but on this point I should prefer the judgment of others more competent to speak than myself.

Mr. Malan will not, I hope, think these remarks are made in a controversial spirit, but simply with the view of contributing a mite towards solving a question in the economy of a flower which is at once as interesting as it is beautiful.

SCIENCE has lately lost one of her oldest workers in the person of M. Henri Milne-Edwards, who died on July 29th, at the age of 85. He was known for his Zoological researches on Crustaceans, and in the anatomy and physiology of marine animals of the French coast, for his Cours élémentaire de Zoologie, and his great work on the comparative anatomy of man and animals, which was finished only a few years ago. He succeeded Isidore Geoffroy St. Hilaire as professor of Zoology in the Jardin des Plantes, besides holding at various times other offices. He was the father of M. Alphonse Milne-Edwards.

IT is understood that the Government will apply to Parliament for State aid for the Marine Biological Association on condition that the work is carried on in concert and harmony with the Scotch Fishery Board.

It appears, on the authority of Mr. A. W. Bennett, in a letter to "Nature," that there are in the American flora plants regarded as belonging to the same species as European plants, but with a difference difficult to define but yet recognisable. He instances Osmunda regalis and Pteris aquilina, which are abundant in Canada, but have a general habit which marks them off from the English forms. The American Plantago major is stated, he says, to be distinguishable by the American horses from our wayside weed, though there is scarcely any difference. Some English weeds are turning out the native ones, but the daisy and primrose, it appears, will not naturalise themselves in America.

THE "Colonies and India" in an article on wool growing, after speaking of the successful introduction of the Angora goat into South Africa, suggests the acclimatisation in new countries of the alpaca, vicuña, and llama, at present restricted to South America. The hair of these and other animals is, it says, increasing in demand, and it considers the mountainous districts of South Africa probably better adapted for the alpaca than the plains of Australia, where an attempt to introduce this animal did not meet with the success expected.

FROM a paper published in the same journal it appears that Messrs. H. B. Dixon and H. F. Lowe have shown that by the ignition to a white heat of a platinum wire in a well-dried mixture of carbonic oxide and oxygen gases in the required proportions, the gases may be made to combine. No flame was visible round the wire and apparently no explosion took place.

IN the same journal Mr. Thomas Turner describes some experiments with relation to the influence of silicon on the properties of cast iron. They lead, he says, to the conclusion that, at all events under the circumstances given, a suitable addition of silicon to cast iron may considerably increase its tenacity, a

result in accordance with previous opinion as quoted by Mr. Turner.

THE result of experiments on the leaves of Euonymus japonica, by P. P. Deherain and L. Maquenne, is said to indicate that the respiration of leaves is not accompanied by a simple change of oxygen into carbonic acid gas, but that an internal combustion takes place in them similar to fermentation, the effect being the evolution of more carbonic acid gas than equals the oxygen supplied. An abstract of the author's paper may be found in the Journal of the Chemical Society for August.

A NEW Volume of the "Nature" Series (Macmillan) is expected, the author being Sir John Lubbock, and the subject "Flowers, Insects, and Leaves."

It is said that Professor Huxley has been asked to retain his post as Dean of the School of Science, South Kensington, and to direct generally the course of biological teaching there.

THE ability of salmon to jump up waterfalls is the subject of some interesting details given by Professor A. Landmark, chief director of the Norwegian Fisheries, of which a notice may be found in "Nature." He states that under some circumstances salmon have been found to jump sixteen feet perpendicularly, and that he knows this by having seen them jump across two masts three and a half feet apart which have been placed across the river about sixteen feet above the water, at the Hellefos, in the Drams River, at Haugsend. He even says that some salmon when jumping a perpendicular fall are able, if they strike the fall straight with the snout, to remain for a minute or two in the falling mass of water should they happen not to clear the fall at one jump; after which with a switch of the tail the rest of the fall can be cleared.

IN a report by Mr. S. Stack, Director of Agriculture in Assam, an extract from which may be found in the "Entomologist" for August the author in considering Assam as a source of supply for the English silk market says the wild silkworms of Assam are out of the question, being much too scarce. Of domesticated worms there are the mulberry worm (Bombyx textor), the muga worm (Antheræa Assama) and the castoroil worm (Attacus ricini). From the two latter Mr. Stack thinks something might be done, in the export not of the thread but of the waste cocoons, those from which the moth has been allowed to eat its way. It appears that from waste cocoons imported from India or China the manufacture of silk plushes and similar fabrics forms a flourishing branch of the English silk industry.

It appears that the authorities at South Kensington do not intend to appoint a successor to Professor Huxley, as Professor of Biology at the School of Science, but have considerably increased the salary of Mr. Howes, Professor Huxley's assistant.

It seems only too probable that ballooning has cost another life. Mr. F. A. Gower, who was associated with Mr. Bell in telephone improvement, left Cherbourg on July 18th, to cross the Channel in his balloon, and has not been heard of since.

MR. A. GRAHAM BELL describes in "Nature" some experiments which were made in his presence of the method proposed by Mr. F. Della Torre, of Baltimore, for preventing the collision of ships with icebergs during a fog or with other ships. A musket with a speaking trumpet attached to the muzzle was fired with blank cartridges at passing vessels, and after a longer or shorter interval an echo was heard. This was the case when the ships were as much as appeared to be a mile off. An echo was even obtained from a small tug-boat approaching the launch on which the experiments were made. It seems that a return of sound is caused also by the ripples on the surface of the water, the effect being in this case like the rolling of thunder and lasting for some seconds.

THE hundredth birthday of M. Chevreul, the chemist, perhaps the oldest man of science living, takes place on August 31st, he having been born in 1785, and preparations have been made by Paris students for its celebration.

IT is stated in "Science" that Professor Tyndall generously gave the net result of his American lecturing tour in 1872-3 as a fund for the education of young physicists at European Universities, but that as difficulties arose in this disposal of the fund, the gift, which has in the meantime accumulated to thirty-two thousand dollars, has lately been divided by Professor Tyndall equally between Harvard, Columbia College and Pennsylvania University for the maintenance of graduate scholarships or fellowships in physics.

A BIOGRAPHY of Mr. Darwin by his son, Mr. G. H. Darwin, is expected to be published before the end of the year.

FROM a report in the "English Mechanic" of a lecture delivered by Dr. P. Ebell at Hanover, it appears that the effect of "grass bleaching" has been shown by previous investigation to be due not to ozone, as was supposed, but to oxygenated water or hydrogen peroxide, which forms an oxidising agent having the advantage over those practically employed of not injuring the material. It is said that the difficulties of preparing oxygenated water on the large scale have been overcome, a three per cent. solution (by weight) being obtainable at a moderate price and in any quantity, and that it may be considered as the bleaching agent which is to rule in the future.

A NEW Soldering material for sealing up food-tins is said to have been patented, consisting of a solution of lactic acid and glycerol in water, for which is claimed a freedom from the ill-effects which have been attributed to chloride of zinc.

MICROSCOPY.

COLE'S STUDIES IN MICROSCOPICAL SCIENCE.The last set of these studies received consists of slides showing a transverse section of a feather in its follicle; vertical section of female receptacle of marchantia, showing archegonia; lung tuberculosis; and a transverse section of tail of puppy; together with the accompanying chromo-lithographs and text.

THE JOURNAL OF THE ROYAL MICROSCOPICAL SOCIETY.-The August number contains a paper by Messrs. F. R. Cheshire and Watson Cheyn on Bacillus alvei; the Cause of Foul Brood in Bees, illustrated by two plates (see this vol. p. 114); a paper by Dr. R. L. Maddox, on Feeding Insects with Bacilli; an Account of Four New Species of Flosculari, and Five other New Species of Rotifera, by Dr. C. T. Hudson, illustrated; and the summary of current researches.

THE JOURNAL OF MICROSCOPY.-The July number of the Journal of Microscopy and Natural Science, the Quarterly Journal of the Postal Microscopical Society, contains papers on Cystopus, or White Rust, by Mr. George Norman, F.R.M.S., illustrated; on Mounting Beetles, &c., without pressure, by Robert Gillo; on What is a Plant? Part ii., by H. W. S. Worsley-Benison, F.L.S.; on Chironomus Prasinus, Part ii., by A. Hammond, F.L.S.; on Animal Metamorphosis, Part ii., by J. B. Jeaffreson, M.R.C.S., illustrated; the Microscope, and How to Use It, Part iii., by V. A. Latham; and on Diatoms in the Stomachs of Shell-Fish and Crustacea, by E. B. Courroux. There are three plates of figures at the end.

THE ANATOMY OF THE COCKROACH.-In reply to J. H. Moorhead, I venture to give the following hints, until some friend comes forward who is better able than I am to do so. There have been some excellent slides circulated in the Postal M. Boxes mounted by one of our members, Mr. A. W. Lyons, illustrating these very articles a few weeks ago. The wing of a male cockroach may be bleached in the following solution. Hydrochloric acid, gtt. (drops) x. ; chlorate of potash 3ss; aqua 3j. This will render antennæ and wings transparent. Wash well, dry and mount in C. balsam and benzole. Many are rendered transparent enough by merely soaking in turpentine. Instead of the above, a weak solution of chloride of lime may be used, by which means the nerves in antennæ will be well seen. I have some mounted in glycerine jelly, first soaking them in equal parts of glycerine spirit and water. Elytron: after soaking in turpentine, cleaning and drying, soak in benzole and mount in benzole and balsam. Gizzard is separated from other parts, cut open, soaked in potass, wash well, mount as above or in gly. The gizzard may be obtained by holding insects firmly with pair of tweezers, and with back of dissecting

knife draw the head from the body, the head brings with it the stomach, gizzard and chief portion of digestive organs. Eyes, after being cut from the head, are soaked for a short time in liquor potass; they may be mounted dry, the facets show well; or soak in equal parts of gly. spirit and water, and mount in gly. jelly. Tongue mount as above. Spiracles soak and mount as above, but to see them properly, the skin must be stretched to show the part between the segments. The salivary glands sent to P. M. Soc. boxes by Mr. A. W. Lyons were stained carmine and mounted in C. b. and benzole.-V. A. Latham.

ZOOLOGY.

THE AIR-BLAdder of Fishes.-A very interesting paper on this subject by Mr. Charles Morris is printed in the "Proceedings of the Academy of Natural Sciences of Philadelphia." He describes the airbladder as at present most generally a closed sac, containing, in fresh-water fishes, nearly pure nitrogen; in ocean fishes, particularly in deep swimmers, a sometimes considerable excess of oxygen. He considers that the air-bladder is not now an organ of functional importance, though it may serve certain uses, such as to raise or lower the fish in the water, to keep its back uppermost, to raise or depress the fore part of the body, &c. He looks upon it as a survival of a breathing organ, and as being now on the road to extinction. This view he supports by reference to embryological evidence and to the condition of existing ganoids and elasmobranchs, as affording indications of the possible state of matters during the Silurian and Devonian period when these two orders were abundant. Existing elasmobranchs are destitute of air bladders, both in the larval and mature stages; while existing ganoids possess one which retains a fully-developed pneumatic duct in the mature stage. The sub-order of the Dipnoi possesses a bladder functionally active as a lung. Of these latter the Australian lung-fish (Ceratodus) has a single air-bladder with symmetrically arranged breathing pouches, and is supposed to breathe with its lungs when the water is muddy or otherwise unfit for use. Finally Lepidosiren and Protopterus have completely formed lungs of cellular structure with two lateral chambers and a pulmonary artery. Mr. Morris thinks that not only may the ancient fishes have used their air-bladders for the occasional direct breathing of air when the water was thick or muddy or lacking in sufficient aeration, or when the pools dried up, though it was such causes as these that probably led to the original development of the airbreathing organ, but that in the absence of foes in the shape of vertebrate land animals they may have gained the habit of leaving the water temporarily in search of food. Since even now, when so many

active enemies are to be found in the land, many fish do invade the shore, and some even climb trees, he is of opinion that it is quite possible that in the early period when it could be done without danger, very many fishes may have paid temporary visits to the land.

LIMNEA STAGNALIS A PAPER-FEEDER.-This afternoon I visited the pond on Chislehurst Common, where the variety of L. stagnalis which I provisionally call elegantula abounds. The hot weather had much diminished the size of the little pond, and the waterweed (Potamogeton crispus) is quite insufficient apparently to supply the wants of the very numerous Limnææ as well as an abundance of Planorbis spirorbis. At one particular spot, however, there seemed to be something very enticing, for here the L. stagnalis were gathered together, so that for the space of about a square foot nothing else could be seen. Being curious to ascertain the reason of this vast assembly, I divided the crowd. The attraction was nothing more than an old newspaper, which had probably been blown into the pond, and which was torn to shreds and partly devoured by the ravenous snails. It did not contain anything wrapped in it, the paper was the sole attraction. Helices in confinement, as most collectors are aware, will readily eat paper if they can get nothing better, but I never heard of Limnæa doing so before. I brought some of these snails home and put them into some water with paper, pelargonium and rose petals, leaves of ivy and bracken, and flowers of Vicia cracca. They "went for" the pelargonium petals, and these are already riddled with holes.-T. D. A. Cockerell.

THE NEST OF THE FIFTEEN-SPINED STICKLEBACK.-Professor Karl Möbius says that the seastickleback (Spinachia vulgaris, Flem.) constructs a nest for its eggs and young, employing delicate shallow water plants, making with these a soft rounded mass 5-8 centim. in diameter upon Zostera, seaweed fronds, or piles of landing-stages, which nest the male surrounds with white silky threads, and then keeps watch over. Professor Möbius has been able to throw light upon the previously unknown origin of these white threads. He says they are nitrogenous, made of a peculiar modification of mucine, and are formed in the kidney of the male, which produce it during the breeding-season only; and the male fish has only to swim round the nest while the thread-forming mucus is given off, and this attaches itself to solid objects that it touches. Further details may be found in a translation given in the August number of the "Annals and Magazine of Natural History."

MOLLUSCA IN MANITOBA.-In the "Journal of Conchology" for July may be found a paper by Mr. Robert Miller Christy, entitled "Notes on the Land and Freshwater Mollusca of Manitoba." The writer

observes that it is remarkable that so many species as exist there should be able to do so in a country where the temperature has been known to fall as low as 50.5° F. The absence of shells from the bare open surface of the prairies he attributes to the extensive fires that take place upon them, and refers to his previously-expressed opinion that the absence of earthworms is due to the same cause.

BIRDS OF THE SOLWAY DISTRICT.-" The Naturalist "for August contains the first part of some notes on the birds of the Solway district by Mr. J. J. Armistead, the notes given being mostly due to his own observation, together with observations made at the Ross Lighthouse.

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DRYINUS FORMICARIUS.-In the "Entomolo"for August Dr. E. Capron records the capture of Dryinus formicarius, Latr., at Shiere, and in his note says that it is very rare both in England and other countries; the male is unknown, and nothing is known of the habits of the insect, which, although his specimen is quite three lines in length, he thinks is no doubt parasitic, probably finding its host in the order Homoptera.

THE PERIODICAL CICADA.-This is the title of a Bulletin issued by the United States Department of Agriculture, the author being Dr. C. V. Riley. The Cicada septendecim is an American insect which comes out in broods every seventeen years, while there is also a race, with no perceptible specific difference, of which the broods come out at thirteen-year intervals, and which Dr. Riley has therefore named C. tredecim. Moreover, in both races there are two distinct forms, a larger and a smaller, the former by far the more numerous. The broods come out in different years in different parts of the States, and a list of many broods is given with particulars of their appearances, &c. Every year it is said, for the next seventeen years, except 1887, 1890, and 1892, will be somewhere a cicada year. Speaking generally, the seventeen-year broods belong to the Northern and the thirteen-year to the Southern States.

BOTANY.

THE PRESERVATION OF OUR RARE NATIVE PLANTS.-The Council of the Midland Union of Natural History Societies has taken a most commendable step in issuing a notice drawing attention to the threatened extinction of rare plants, a question which has arisen lately in connection also with the Swiss flora. It is a subject which ought to receive the serious attention of all field-botanists; and indeed, those who collect personally or by agents, in order to sell, are perhaps not all of them beyond the reach of an appeal. At their door much of the mischief is to be laid, but they are not the only causes, in the opinion of the council, who name, besides, the operations of

exchange clubs, the careless and indiscriminate gathering of plants by botanists and students, often with their roots or seeds, and the reckless gathering of large numbers of specimens by individual botanists. Various recommendations given with a view to lessening the evil are—to abstain from countenancing the purchase of native plants from professional planthunters, either for their rarity or for their decorative value; that botanists should make but limited use of exchange clubs, and exclude rare plants from their operations; that they should restrict themselves in the gathering of plants, and even abstain altogether in some cases; and that tourists and amateurs be urged to refrain from collecting rare plants, especially when in flower or in seed, as few of those gathered under such conditions can live after removal. What seems to be wanted is that this matter should become a point of honour among botanists, and if it were widely understood that a true botanist did not pride himself on the number of rare plants he had possessed himself of, a feeling would probably follow that it was no special credit to have such in one's collection, and certainly not to make them an object of eager acquisition. One other recommendation may be added to those advanced by the council, viz., to abstain as a rule from telling the localities where rare plants may be found. The compilers of floras will hardly like this, but as they have the power of doing harm in this direction, it is as well to point it out. Moreover, there is no credit in marching off to gather rare plants whose localities have been learnt from a book. Extinction of species is a thing that has doubtless gone on since the world began; but botanists need not hasten it, and by consideration and the practice of self-denial may do something to hinder it.

WHAT IS A PLANT?-Under this title Mr. H. W. S. Worsley-Benison, F.L.S., in a paper reprinted from the "Journal of Microscopy and Natural Science," enumerates various points which appear to afford distinctions between plants and animals, viz., Form, presence of cellulose, of starch, of chlorophyll, function of locomotion, of digestion, of circulation, presence of nitrogen, function of respiration, of sensation, and lastly, the nature of the food. Under these different headings he gives explanatory remarks and examples, and towards the end of the paper says that the case will be found to be pretty much this, that while many of the points are not distinctive enough, "in the presence of a cellulose coat in the plantcell, in digestion followed by absorption, and in the power to manufacture protein, we find fairly constant and well-marked distinctions; the morphological feature of plants being this cellulous coat; of animals, its absence; the physiological peculiarity of plants, this manufacturing power; of animals, the want of it." The paper forms a very useful summary of the points bearing on this question.