One that I found in a field, could only hop, being quite unable to fly, and another one was found shortly afterwards in the next field in the same condition. The weather at the time was severe, but the cause of this mortality was undoubtedly disease.

NOTES FOR APRIL 1890, BEING AN EXTRACT FROM A LETTER.

The greater and lesser periwinkle were both in flower the beginning of this month. Lilac leaves also about this date; and the hedges are now getting forward in leaf. Young rooks were hatched about the 1st of April, as I find by egg-shells thrown out of the nest. What a large quantity of sticks the rooks drop when busy building, either from their not being suitable, or by accident! There is enough wood lying under a few elm trees (which contain a small rookery of about eighteen nests) to last a person for lighting a fire every morning for a fortnight. Snowdrops and crocuses have all disappeared now from our gardens. An interesting fact connected with the Christmas-rose I have lately observed in our garden. This plant was in flower about Christmas-time here, and were all faded away, when about the end of March I saw with surprise another flower half opened, which had shot forth from the stem where the flowers of December had died off, and now (April 7th) I notice others on some of the other stems, so that it seems as if it flowers twice in a season. There is now nothing more pleasant than to ramble through the meadows on a clear evening at this time of the year. The rich and clear song of the blackbird reaches us from some leafing hedgerow a little way off, where he sits perched on the top of some bush, cheering his less dusky spouse, as she is keeping guard over her blue eggs, snugly placed in the nest at the bottom of the bush. During the second week of this month the currant and gooseberry bushes came into flower. Ground-ivy was in flower on the 9th, song-thrush with young on the 10th. Fieldfares I observed on the 13th, also a large flock of them the day before. Cowslips were in flower under hedges on the 13th, and dog-violets and wood-anemones were in flower on the same day. The ivy-leaved speedwell abounds amongst the green corn in a cornfield called "Mill-ditch." Blackthorn was in flower on the 13th of this month along the hedge at the bottom of the same field.

MAY.

The trees are now putting on their summer dress, and the hawthorn scents the evening gales. The anemone, primrose and violet have faded away, but others have taken their places, such as the blue-bell, or wild hyacinth, purple orchis, germander speedwell, and tormentil. The birds are as yet singing merrily in the hedges and groves, but in a few months' time all our singing-birds will be silent with

WILL

By CANON RUSSELL.

you kindly allow me to bring under

notice some facts connected with the luminosity of plants which have been recently attracting my attention? I became acquainted with them quite accidentally, in the following way.

On the evening of the 16th of June, 1889, I happened to be taking a stroll round the Rectory Garden, and passing by a fine plant of the common double marigold (Calendula officinalis) of a deep orange colour, I was struck by a peculiar brightness in the appearance of the flowers. After watching for a few seconds, I observed, to my great surprise, that corruscations of light, (like mimic lightning) were playing over the petals. Thinking that I might be only the victim of an ocular illusion, I brought out other members of the household, and asked them to report exactly what they saw. Some perceived the flashes readily enough, but others only slowly and after patient observation, all eyes not being equally sensitive to such rapid vibrations of light.

These performances commenced about 8.30 P.M. and continued for perhaps under an hour. I afterwards ascertained, that much later on, when it was almost dark, the whole plant seemed to glow with a sort of pulsing phosphorescence. The common nasturtium, and the scarlet geraniums showed a like luminosity. Closely connected with their appearances, I could distinctly see a blue vapour of extreme tenuity given off from the leaves of some of these plants, if not from all, in open daylight or under lamplight. This can be best seen by holding the leaf against a dark background, and letting the light fall upon it at various angles. These two last phenomena were not as readily detected by other persons as were the sparks of the marigold. They were made, however, abundantly evident to all eyes in the following way. I put a leaf of the nasturtium on the stage of a microscope-and, having focussed it for the central spot from which the nerves branch off, under an inch and a half objective, I brought it into a room nearly dark. Looking at it then through the microscope I found that the leaf could be distinctly seen almost by its own light. The appearance

indicated by Mr. Lord, which, I think, should not be allowed to pass without comment in the pages of SCIENCE-GOSSIP.

I would first point out that, by some misunderstanding, Mr. Lord assumes that Mr. Gosse's phrase "habitual protrusion of the head," refers to some inability of the rotifer to withdraw its head between the plates of the lorica. It is true that the figure (after Ehrenberg) of Distyla Hornemanni in "The Supplement" represents this species with its head protruding and its cilia extended, although otherwise much retracted, but I am inclined to deny credence to that remarkable position until I see some Distyla assume it. On the contrary, Mr. Gosse's words can only mean that as compared with the very sluggish, timid or indolent habits of the Cathypnæ, the Distylæ are more usually active and less prone to indulge in naps (?) when under observation. All the Distyle I have seen were perfectly able to retract their heads within the lorica plates.

In the next place, Mr. Lord appears to have overlooked the fact that Eckstein founded the genus

Fig. 183.-Ditto, brain X 540.

Fig. 182.-Ditto, ventral view.

Distyla in 1883; and it has therefore priority over Cathypna instituted by Mr. Gosse in 1886, at the same time that he set apart the family of the Cathypnadæ, to include not only Cathypna, but, inter alia, the Distyla of Eckstein, which he thus distinctly accepted and confirmed. If, therefore, the distinctions set up between the two genera were shadowy or insufficient, it would be the genus Cathypna that would have to give way, not the genus Distyla.

Again, if a species be so balanced between two genera as to appear to belong to one when extended, and to the other when retracted, there can be no question that the extended position being the natural one, the species must be assigned to that genus to which it conforms when extended or active, and I submit that on Mr. Lord's own showing, his

two species are certainly Distyle, and his description and figures as certainly indicate that genus.

I observe that in his quotation of Mr Gosse's remarks about Distyla, he omits the word lengthened. Mr. Gosse says "the lengthened and flattened form." The omission is of course unintentional, but the character is important and fits Mr. Lord's species.

As to the distinctions between the two genera, these have been set forth in such a plain and concise way in the criticism of Mr. Lord's article which appeared in the December issue of the Journal of the Royal Microscopical Society, that I may perhaps be permitted to quote the sentence for the benefit of those who have no opportunity of seeing the original. "In Cathypna the whole trunk is loricated and the creature when extended is dorsally arched; but in Distyla only the hinder portion of the trunk is loricated, the forepart having a membranous covering and the creature, when extended, is comparatively flat, or, as it is termed, depressed." Save that the writer omits to draw attention to the usual outline of the two genera when extended, Cathypna

less complete and no points are to be seen; and I have found dead specimens of the same species, from which the head and all interior parts have vanished, yet displaying an apparently permanent shell much exceeding that shown in retraction. I conclude that the restricted use of the term may be convenient but is possibly incorrect, and that the absence of the two lateral points is a character that especially requires careful verification.

Although among some genera of the Rotifera mere size is an unsafe guide to identification, there are others in which, regard being had to mature individuals only, the dimensions of the different species are closely adhered to. Among the Cathypnadæ I have found the variation to be very slight, not I think more than 10 per cent., if so much. It would therefore be an assistance to those who hope

being generally ovate, and Distyla of the form of a long ellipse, the above sentence perfectly and briefly summarises the points of difference.

All other points in the generic characters are, I think, either common to both genera, as "lorica closed behind, toes two, selvage-like thickenings of the lorica around the foot," or of secondary importance as depending upon individual estimate, such as lateral inangulation strong or feeble, or of habit, such as "the habitual protrusion of the head" and "the more constant activity." All these may be safely disregarded, when there are present the leading characters pointed out in the sentence quoted.

There appears to be some confusion as to the meaning of the term lorica, in respect of the genus Distyla. I am not myself quite clear that it ought to be restricted to that portion of the covering of the trunk, which appears to remain stiff and hard when the animal is retracted. I have found that different individuals of the same species do not always retract to the same degree, that whilst at one time two short lateral points (as described in many species) are easily visible, at another time the retraction will be

Fig. 186.-Distyla musicola. Ventral aspect. X 480.

Fig. 187.-Monostyla cornuta. X 320.

to meet with Mr. Lord's forms, if he would state particulars of the measurements when extended and when retracted. It is also useful to know the exact shape and length of the toes. There is in nearly every genus, one point in which the species appear to agree to differ. In the genus Macrotrachela it is the spurs, in Distyla and Cathypna the toes.

I append descriptions of two species, which appear to me very distinct from any of those yet described, and of a Monostyla closely related to, but not identical with, the common and well-known M. cornuta.

Distyla depressa.

Sp. Ch.-Lorica much flattened, ovate, truncate at both ends; anterior edges, ventral excised in moderate curve, dorsal straight; two short lateral points shown in extreme retraction; dorsal plate shorter than ventral and narrower behind; toes blade-shaped, acute, slightly decurved; brain three-lobed.

The lorica is very flat, the average thickness of fairly natured specimens being rather less than onefourth of the length of the dorsal plate. It is free from flutings or tesselation and moderately firm. In retraction the outline of the trunk is scarcely altered, the proportion of loricated to membranous covering being unusually great. In lateral view some irregular wrinkles are visible in the integument lining the lateral infold, which is well-marked (see dotted lines Fig. 180), although the plates are but little separated. The dorsal plate, while in front as broad as the ventral, is rather narrower behind, and is abruptly and somewhat convexly truncate. The ventral plate is excised anteriorly, permitting the head to be bent down as shown in lateral view. The outline is posteriorly completed by the dilated basal foot-joint, which appears to be almost fixed and to have even less freedom than usual in the genus. It is difficult to trace lines indicating the junction of this joint with the trunk on either dorsal or ventral side, but those I have shown are, I think, correct. Indeed, the joint is little more than a partly shelly, partly membranous framework protecting and supporting the sub-square lower foot-joint, which issues from the under side and pivots on a blunt point arising from the ventral plate. The toes, seen vertically, are widest at the base, are then slightly pinched in, again widen and finally taper to acute points without either claws or shoulders. This curvature is confined to the outer edges; the inner being quite straight, yet with a slight rugosity near the base. Seen laterally the upper edges are decurved and the lower nearly straight.

The ample brain is in front bluntly pointed, but widens into three lobes, of which the central is the greatest and bears near the inner side at its base the bright rose-red eye. The wedge-shaped outline of the prone face is interrupted by two knob-like projections whose nature and origin I have been unable as yet to determine. The powerful mastax is well forward, and I believe I have seen the jaws slightly protruding into the buccal cavity. An oesophagus of moderate length is attached to the inner side of mastax and passing down it, proceeds to the stomach, the lower part being in constant and rapid undulation. The stomach, surmounted by the usual gastric glands, is separated by a distinct constriction from a capacious intestine, and in both ciliary action is apparent. The vascular system embraces lateral canals, at least three pairs of vibratile tags, and a small contractile vesicle having a short period. Two band-like muscles pass from the head down the back. Length;-total, 1 inch, toes about inch, breadth inch.

In a gathering made in March 1890, from the River Lea, below the Lea Bridge Waterworks, and which I had placed on one side, I found some months later a flourishing colony of Rotifera. The species were few but very select, the most conspicuous being Adineta oculata, only hitherto found, I believe, near

Aberdeen. Along with it were many examples of this Distyla, some Callidina elegans, and some others. The three forms named continued to flourish up to the end of November, when the severe weather wrought havoc among the colony. The Distylæ succumbed, but the other two species survived and now after thirteen months the stock seems fairly vigorous. It is noteworthy, that the supply of water has never exceeded two ounces, any loss from evaporation having been simply replaced from time to time from the household supply, that no artificial feeding was resorted to, and that no pond weeds were present, the plant side of the balance of life being represented principally by Scenedesmus and a scanty growth of Oscillatoraceæ.

Distyla musicola.

Sp. Ch.-Lorica ovate, flattened, both anterior edges truncate, almost straight, two very short lateral points seen in utmost retraction. Dorsal plate rather broader and longer than ventral, and rounded behind. Ventral plate with a definite and shelly central portion almost plane, from which a less stiff integument recedes laterally to the edge of the infold, and posteriorly merges into that of the dilated basal joint of the foot. Toes, tapering, acute, without claw or shoulder.

Numerous dead examples have occurred amongst the sediment of water drained from Sphagnum, but I have only as yet found one living specimen. The remains seen have however shown the creature in every position, and I find that as in D. depressa the outline of the trunk is not greatly changed by retraction, and that extended the form is that of a long oval, rather than that of an ellipse. The head is wedge-shaped, the face rather prone, and the mastax normal. Some very delicate markings can sometimes be seen on the shelly portion of the ventral plate. The membranous lining of the infold is so wrinkled as to give a peculiar scalloped appearance to the lateral margins. The basal joint of the foot is as in D. depressa, but even less distinct. The lower joint is much narrowed at the base. The blunt point on which it pivots, appears however to arise from the upper joint and not from the ventral plate. The toes are thickest just above their middle and taper thence to fine points. They appear straight in vertical view, but seen laterally, they are slightly decurved, with upwards-turning points.

This species resembles very closely the widely distributed M. cornuta and differs from it principally in being about one-fourth smaller, and rather narrower in proportion, and in having both the anterior edges of the lorica excised and to a greater degree. Mr. Gosse states that in M. cornuta the front of the lorica is shallowly incurved, that the anterior dorsal edge is slightly less incurved than that of M. lunaris, but that the ventral edge has its margin quite straight. I think that here he is slightly in error, and partly on this account, and partly for the sake of comparison with the figure of the new species, I add an outline of the ventral aspect of the lorica of M. cornuta when retracted. This position (not figured by Mr. Gosse) shows the straight occipital edge and the very slightly excavate pectoral edge of the lorica as well as the large basal foot-joint. In the numerous examples I have examined, the occipital edge has always seemed straight and the pectoral slightly excavate, and this structure is exactly what would be necessary to facilitate the bending downwards of the head.

In any case, in M. arcuata, the excision of both anterior edges is much sharper than in M. lunaris. In all other details, in general aspect when extended, and in its sluggish habits, the species is the counterpart of M. cornuta, yet the differences noted, though minute, are constant, and I consider fairly entitle the form to rank as distinct.

Mr. Gosse gives the length of M. cornuta as inch extended. The largest specimens I have measured were about 4 inch, and the average inch, while M. arcuata in the like position averages linch, the lorica alone being about inch. I have found dead specimens very abundantly among the drainings from Sphagnum and I have recently had for a little time a colony in a jar, the bottom of which was covered with some threads of moss, gathered last year and now springing into fresh growth.

My sketches show a broad and a narrow form, apparently the extremes of variation, the former being probably a more mature individual. Young specimens resemble when slowly gliding along, the form which I take (yet with some doubt) to be the M. mollis of Mr. Gosse, which however when in retraction s not to be distinguished from M. cornuta and is therefore equally distinct from the present. Habitat among roots of Sphagnum, Epping Forest.

school of naturalists, that this supposed factor in the transmutation of species is unproven and unnecessary; unproven because the hereditary transmission of characters acquired during the lifetime of the individual has never been experimentally established, and unnecessary because we can explain the phenomena of organic evolution without invoking its aid?

Such is the question which, of all others, is now engaging the attention of the biological world. Closely connected with it is the consideration of Professor Weismann's brilliant contributions to the existing literature of variation and heredity, including a theory of heredity absolutely inconsistent with the conclusion of Mr. Darwin which we have quoted. For the last two years and a half, that is since the discussion on the transmission of acquired characters raised by Professor Ray Lankester at the Manchester Meeting of the British Association in 1887, in which Professor Weismann himself took part-this subject has been prominently before English naturalists. During this period there has been no paper or discussion on the subject, hardly even a reference to it, in the pages of SCIENCE-GOSSIP.* It is obvious that the question is one of the deepest interest, affecting, as it does, the very foundation of our conception of organic evolution. If the "Lamarckian" factor, as it is sometimes called, is a true factor, it must have played an important part in the modification of species. If we are to reject it altogether, a large number of phenomena will have to be explained in other ways; in fact its rejection will entail a more or less important modification of the Darwinism of Mr. Darwin. Apart from these considerations, Professor Weismann's theories of heredity, variation, etc., which differ essentially from those hitherto generally held, are concerned with matters lying at the root of any explanation of evolution. I therefore thought that a series of papers on the subject, which should aim at setting forth, as briefly as possible, the various problems involved, would be of interest to those readers of SCIENCE-GOSSIP who may lack the time or inclination to study the subject more deeply. The method I propose to pursue is, first to state clearly the main question at issue, which turns on the truth or falsehood of what is known as Lamarck's "second law," and to sketch the present position of opinion upon it, then to give an outline of Professor Weismann's hypotheses on the subject of heredity and variation, and finally to try and show the exact bearing of these theories on the question with which I started.

We will commence our brief account of the position of opinion on the subject under discussion, and of how it came to be what it is, by stating the question at issue and then defining our terms. The question in its most general form is: "Can an acquired' character be inherited?"

The above was written in April, 1890.