an intermediate continent. "If this inference should be confirmed by future observations, we should then see how the eocene tropical or subtropical flora of Europe was crowded off the stage by the tropical flora of the miocene, which latter accompanying a depression of temperature, had migrated from America, while the eocene flora had retreated south and east, and is now represented by the living Indo-Australian flora, characterized by its Hakeæ, Dryandreæ, Eucalypti, etc., etc., which form so conspicuous an element in the eocene flora of Europe." Instances in which the miocene flora occurs on the McKenzie River, Disco Island, Iceland, and the Island of Mull are then brought forward to show that this land connection must have occurred to the northward, and that the country was then in possession of a milder climate than now reigns in the same latitude. In discussing the causes which produced this difference of climate Professor Newberry gives his adherence to none in particular, but thinks that the deflection of the Gulf Stream would be the most natural method and at the same time places an objection in the path of the astronomical theorists, which they will find it difficult to combat. It will be remembered by our readers that many of the geologists of the day account for the former presence of a warm climate in the Arctic region, by supposing that the earth has, in former times, passed through a warmer region in space. This cannot be assumed to be the cause in the present instance; for any "cosmical cause, producing a general elevation of temperature on the earth's surface, would have given us a tropical flora on the Upper Missouri, whereas we find in the miocene flora there, as yet no tropical plants." RELATIONS OF THE ROCKS IN THE VICINITY OF BOSTON.* - Professor Shaler regards all the syenites of this vicinity as of sedimentary origin, and rejects the old theory of their Plutonic origin. In this he is supported by the late discoveries of the Eozöon in this vicinity, and by the researches of Professor T. Sterry Hunt, published in the last number of the American Journal of Arts and Sciences." The section of the rocks in the neighborhood of Quincy is described as consisting of a layer of quartzites "to the north of the Quincy Syenite Hills, a hidden section of about three hundred feet thickness, and the Braintree series of two hundred feet. Another section of the Chesnut Hill Reservoir is also de scribed, composed of Cambridge slates for seven hundred feet, Roxbury conglomerate for ten feet, thirty feet more of slate and conglomerate again extending to the edge of the Charles River flats in Brighton, where they give place to a sandstone. * Abstract of Some Remarks on the Relations of the Rocks in the Vicinity of Boston. By N. S. Shaler. Proc. Boston Soc. Nat. Hist., vol. xiii. Dec. 3, 1869. Pamph., pp. 7. NATURAL HISTORY MISCELLANY. BOTANY. ON THE FERTILIZATION OF GRASSES. In gently flowing rivers of tropical America grow many fine aquatic grasses, species of Luziola, Oryza, Leersia, etc. The following note is from my journal under date of December, 1849, when threading in my canoe among the islands of the Trombetas: "This channel was lined on both sides by a beautiful grass - a species of Luziola - growing in deep water, and standing out of it two or three feet. The large male flowers, of the most delicate pink, streaked with deep purple, and with six long yellow stamens hanging out of them, were disposed in a lax terminal panicle; while the slender green female flowers grew on the bristle-like branches of much smaller panicles springing from the inflated sheaths of the leaves that clothed the stem. As the Indians disturbed the grassy fringe with the movement of their paddles, the pollen fell from the antlers in showers," and would, doubtless, some of it, attain the female flowers disposed for its reception. A parallel case to the above is that of the common Maize (Zea Mays L.), where the male flowers are borne in a long terminal raceme or panicle, and the female flowers are densely packed on spikes springing from the leaf-axils. Here the male flowers must plainly expand before the pollen contained in their anthers can be shed on the female organs below, whether of the same or of a different plant. That there are frequent cross-marriages in Maize is evidenced by the numerous varieties in cultivation in countries where it is a staple article of food, as in the Andes of Ecuador, where nine kinds, varying in the color of the grain (through white, yellow, and brown, to black), in its size, consistence, and flavor, are commonly cultivated; besides many others less generally known. In Pharus scaber (H. B. K.) another tall broad-leaved grass, the spikelets stand by twos on the spike-a sessile female spikelet, and a stalked male spikelet. In the fine forest grasses of the genus Olyra, whereof some species, such as 0. micrantha (H. B. K.), rise to ten feet in height, and have lanceolate leaves above three inches broad, and a large terminal panicle, with capillary branches, like those of our Aira caspitosa, it is the lower flowers that are male, with large innate (not versatile) anthers, and the upper that are female, with two large stigmas, that are either dichotomously divided, or clad with branched hairs, thus exposing a wider surface to the access of the pollen. And as the panicle is often pendulous, many of the male flowers, although placed lower down the axis, are actually suspended over the terminal female flowers. It is generally to be remarked of declinous grasses, that either the male flowers are very numerous, as in Zea Mays, or the stamens are multiplied in each male flower, as in Pariana, Leersia, Guadua, etc.; or the stigmatic apparatus of the female flowers is enlarged, so as almost to insure impregnation, as in Olyra and Tripsacum. In the Bambuseæ I have gathered, belonging to the genera Guadua, Merostachys, and Chusquea, the flowers are more or less polygamous, and the stamens of the male flowers often doubled. But there is scarcely a genus in the whole order which is not described as having some flowers by abortion, neuter or male, and especially those that have biflorous spikelets, such as the Paniceæ. Some grasses, of normally hermaphrodite genera, are not unfrequently truly unisexual, such as certain species of Andropogon. I have occasionally seen panicles of Orthocladus rariflorus (Nees), a grass peculiar to the Amazon, quite destitute of stamens, and therefore purely female. To come home to our own country: Is all the pollen wasted that a touch or a breath sets free from the flowers of grasses in such abundance? Watch a field of wheat in bloom, the heads swayed by the wind, lovingly kissing each other, and doubtless stealing and giving pollen. Consider, too, that throughout Nature, heat or moisture, or both, are essential to the emanation of the impregnating influence. In all our Festuceæ, as well as in Cynodon, Leersia, and some other genera, the stigmas are protruded from the side or from the base of the flower at an early stage, often before the stamens of the same flower are mature - thus as it were inviting cross fertilization from the more precocious stamens of other plants which are already shedding their pollen. All who have gathered grasses will have remarked that some have yellow anthers, others pink or violet anthers; and that anthers of both types of color may co-exist on distinct individuals of the same species. The same peculiarity is just as noticeable in tropical grasses, and (without professing to give a complete physiological explanation of it) this is what I have observed respecting it. The walls of the anther-cells are usually of some shade of purple, but are so very thin and pellucid, that when distended with mature pollen the yellow color of the latter is alone visible. When the pollen is discharged, the anthers resume their original purple color, shortly, however, to take on the pallor or dinginess of decay. Where the anthers emerge of a purple hue, and change from that to brown, it will probably be found that they have discharged their pollen while still included in the flower. These observations, made without any reference to the question now in hand, require to be renewed and tested: and in them, as in all that precedes, I am open to correction. Of grasses with bisexual flowers, there are two ways in which the ovary may be fertilized, namely, either by the pollen of its own flower (closed or open), or by that of other flowers, after the manner of the declinous species. In the latter case, the pollen may be transported by the wind, or in the fur of animals (as I have observed the seeds of Selagin ellas in South America), or in the plumage of birds. The agency of insects has not been traced in the fertilization of grasses, but may exist. The little flies I have seen on the flowers of grasses seemed bent on depositing their eggs in the nascent ovaries, but may also have aided in cross-fertilization. In the Amazon Valley grasses are often invested by ants, who, indeed, leave nothing organic unvisited throughout that vast region; and they also, I think, cannot help occasionally transferring grains of pollen from one flower to another. The flowers of Palms and Grasses agree in being usually small and obscurely colored, but contrast greatly in the former being in many cases exquisitely and strongly scented, whereas in the latter they are usually quite scentless. The odor of Palm-flowers often resembles that of Mignonette; but I think a whole acre of that "darling" weed would not emit more perfume than a single plant of the Fan Palm of the Rio Negro (Mauritia Carará Wallace). In approaching one of these plants through the thick forest, the sense of hearing would perhaps give the first notice of its proximity, from the merry hum of winged insects which its scented flowers had drawn together, to feast on the honey, and to transport the pollen of the male to the female plants; for it is chiefly diœcious species of Palms that have such sweet flowers. The absence of odoriferous flowers from the grasses seems to show that insect-aid is not needed for effecting their fecundation, but does not render its accidental concurrence a whit less unlikely. That grasses, notwithstanding their almost mathematical characters, vary much as other plants do, is plain from the multitude of osculating forms (in such genera as Eragrostis, Panicum, and Paspalum), which puzzle the botanist to decide when to combine and when to separate, in order to obtain what are called "good species." Hence the conclusion is unavoidable that in grasses, as in other plants, variations of surrounding conditions induce corresponding modifications of structure, and that amongst the former must be enumerated cross marriages, however brought about. If the flowers of grasses be sometimes fertilized in the bud, it is probably exceptional, like the similar cases recorded of Orchids and many other families. To conclude the more I ponder over existing evidence, the more I feel convinced that in its perfect state every being has the sexes practically separated, and that natural selection is ever tending to make this separation more complete and permanent; so that the hypothesis of Plato, that the prototype even of man was hermaphrodite, may one day be proved to be a fact! - DR. R. SPRUCE, Scientific Opinion. [See his paper in Journ. Linn. Society.] FUNGI ON INSECTS. - Dr. Bail of Danzig, in a recent pamphlet, calls attention to the various kinds of fungus that are parasitic upon the larvæ of different insects, and his investigations are of some practical importance in relation to a possible check to the destruction of forest-trees, which goes on to an enormous extent in North Germany, through the ravages of caterpillars. In certain seasons these caterpillars appeared to be attacked by an epidemic, their bodies being swollen to bursting, and white threads being visible between the rings of the body, which seemed to issue from the body itself. In this condition great numbers were found still clinging to the leaves. The destroying agent had been identified by Dr. Reichhardt of Vienna as the mycelium of a fungus which he named Empusa aulicæ. The distribution of the Empusa is very considerable; the only order of insects which is not at present known to be subject to their attacks being the Neuroptera (dragon flies, etc.); they are known to be parasitic upon Coleoptera (beetles), Hymenoptera (bees, ants, etc.), Lepidoptera (butterflies and moths), Diptera (flies and gnats), Orthoptera (crickets, etc.), and aphides, either in the larva or perfect condition, on water-insects, and even the same species on amphibia and fishes. Not only is their distribution over so many different animals remarkable, but also the prodigious rapidity of their development in the individual. The common house-fly is, in some years, destroyed by this parasite in vast numbers, and the dung-fly has been in certain districts almost annihilated. In the forests of Pomerania and Posen the caterpillars have been killed by it in such quantities that it may be considered to have saved the trees from total destruction. The fungi which Dr. Bail found to be the most destructive to insect life were those described by authors as Cordyceps militaris, Isaria farinosa, and Penicillium glaucum; the two latter forms he inclines to unite as different stages of growth of the same plant. The Academy. INSECT-FERTILIZATION OF FLOWERS. In an article contributed to "Scientific Opinion" by Professor Delpino, he passes from orchids, which since Darwin's work upon them have attracted much attention in this respect, to the related families, one of which is familiarly represented in our gardens by the Canna, or Indian Shot. Here the arrangements depends upon the viscidity of the pollen, and the bursting loose of the style; the pollen is first deposited on an expansion of the style, whence it is taken away by the insect, to be deposited upon the stigma of the flower next visited. - COLLECTED NOTES ON AMERICAN OAKS. Concluded. A. De Candolle, in "Prodromus" XVI, 2, 1864, describes two hundred and eighty-one species. Of these one hundred and twenty-two are American; of which twenty-nine are doubtful. He admits Q. olivaformis Michx., bicolor Willd., grisea Lbm., pungens Lbm., hastata Lbm., Leana Nutt., as species. Thirteen species from Endlicher's list are made varieties of others; sixteen are synonyms of others. De Candolle proposes three new species: Q. Lindeni (collected in New Grenada in 1842, by Linden), Wislizeni (1846, in New Mexico by Wislizenus), and omissa (from Seemann's collection, but omitted in "Plantæ Hartwegianæ "). Q. dumosa Nutt., and acutidens Torr., are not mentioned. Counting these omitted species, and dropping olivaformis and Leana as such; then uniting grisea with oblongifolia |