apical cell, and growing in length by division, by oblique septa, which takes place in that apical cell. He states that the leaves are in triple whorls, each whorl consisting of two undivided aerial leaves and a multifid aquatic leaf. There has been a good deal of discussion as to the nature of this latter leaf. It is so much divided as to present the appearance of long filiform fibres, and the writers cited by Dr. Pringsheim have entertained different views respecting it. Bischoff states that Salvinia has leaves in pairs, and that on the under side, under each pair, there originates a thick bundle of filiform floating radical fibres. Schleiden treats the divided leaf as a pendent branch springing from the base of the leaf-stalk, and bearing the fruit. Other views, which we have not space to go into at length, have been entertained by Mettenius, Nägeli, and Hofmeister. Dr. Pringsheim traces out, with great care, the origin of the three organs from their primary cells, pointing out that in the divided leaf, the growth of the lamina in breadth is suppressed. He then says, "The difference, therefore, "which I see in the development of the aerial leaves and the aquatic "leaf is the same as that between the development of undivided leaves "with abundant parenchyma and multifid leaves with little paren"chyma. It is known that the latter form of leaf is very frequent in "the submerged leaves of water plants, and I see therefore nothing "against the supposition that Salvinia, like many phænogamic aquatic plants, has leaves of two sorts, one sort being submerged " and multifid, the other floating and undivided." Before proceeding to the second section, in which we shall have to call attention to some discrepancies between the observations of Dr. Pringsheim and those of Dr. Hofmeister, we may state that the former considers the fruit of Salvinia as metamorphosed lateral segments of the aquatic leaf. He says, that the uppermost marginal cells, which in barren aquatic leaves become new segments, are transformed by a process of cell-formation into the fruit.

66

The fruit of Salvinia consists, as is well known, of two kinds of bodies, viz. the macrosporangia, from which the prothallium, and ultimately the female organs and the embryo of the new plant are produced, and the microsporangia, which yield the vesicles in which are contained the spiral filaments or spermatozoa, now generally admitted to be the male organs. The macrosporangia and the microsporangia are contained in separate capsules or sacs, the former contain a single large spore (the macrospore), the latter a number of smaller bodies, the microspores. From the discrepancies in the

observations of Pringsheim and Hofmeister, above alluded to, we cannot but conclude that these bodies are as yet but imperfectly understood, and it may be useful to mention some points on which these two experienced and accurate observers are at variance. Pringsheim states, at p. 512, that the microspores form a single layer of cells within the coat of the microsporangium. Hofmeister does not distinctly say that the microspores are not in a single layer, but we should collect from his sectional figure,* that he considers the microspores agglomerated, and this would accord with the figure by Griffith, published in his posthumous work, and with that of Payer, in the "Botanique Cryptogamique." Pringsheim states that the cellule in which the spermatozoon is contained is not stripped off before the entry of the latter into the archegonium. Here, again Hofmeister's figurest seem to point to a contrary conclusion, but Pringsheim himself is doubtful whether the cilia and tail of the spermatozoon are within or without the cellule. We do not understand Pringsheim's statements that the cellules, which Hofmeister procured by pressure of the microsporangium, were manifestly only young antheridia, and that they afford no clear idea of the development of the latter organs and their spermatozoa. No doubt Hofmeister's account is not reconcileable with Pringsheim's view that the antheridia are normally produced by the growth of the inner membrane of the microspore whilst still within the microsporangium, but it does not follow that Hofmeister may not be right in supposing that the antheridia ripen their spermatozoa after becoming free. His figures (Pl. xliv. figs. 29, 30) of half-emptied antheridia are very like Pringsheim's perfect ones. As to the escape of the spermatozoa, the two authors are again directly at variance. Pringsheim says that the spermatozoa are not freed from the antheridia by the mere decay of the microsporangium, but always by the protrusion of the inner membrane of the microspores through the coat of the microsporangium, and the regular rupture of the antheridial cells. Hofmeister speaking of the spermatozoa, says, "There can be no doubt that, in "the regular course of nature, they are set free from the micro"sporangia by gradual decay of the walls of the latter."

It would be difficult, without figures, to go into the details of

See Hofmeister on the higher Cryptogamia, Ray Society's Translation, Pl. xliv. fig. 26.

† Pl. xix. figs. 31, 32.

their differences, as to the structure of the archegonium. We cannot but think it improbable that Hofmeister has entirely misunderstood the structure of the neck and the formation of the canalicular passage of the archegonium. Pringsheim's explanation of the latter may be correct, although it involves the supposition that Hofmeister confounded the embryonal vesicle with the cell destined to form the spermatozoal canal, a supposition which it is hard to accept. Moreover, we cannot understand how, according to Pringsheim's theory, the spermatozoa could obtain access to the embryonal cell, for, assuming the so-called canal-cell, and with it the membrane of the central cell, to be ruptured at the apex, the lower portion of the membrane of the canal-cell would still (unless it were absorbed, a fact of which we find no mention) remain as a barrier to prevent the free passage of the spermatozoa.

Perhaps some of our readers may have the opportunity of investigating for themselves the above disputed questions, and, if so, we would venture to submit the following considerations. The first, viz. whether or not the microspores form a single layer cannot be difficult to solve. An examination even of dried specimens, in sufficient number, would decide it. The question, whether the cellule enclosing the spermatozoon is stripped off before the latter enters the archegonium can hardly be decided by the examination of active motile spermatozoa, but if a sufficient number of such spermatozoa are placed under the microscope, and their motion arrested by iodine, the structure would not be difficult to make out. The questions as to the protrusion of the antheridial tubes, the decay of the microsporangia, and the escape of the mother-cells of the spermatozoa, would depend upon careful observation of living Salviniæ, which, unfortunately, in this country, cannot be carried out; not that there would be any difficulty in cultivating the plant, but the point could hardly be satisfactorily decided otherwise than by observations in its natural habitat. The questions as to the structure of the archegonium are attended by peculiar difficulties of observation and manipulation, requiring much leisure and an amount of patience and industry, possessed by few observers; owing to these difficulties, the results to be arrived at are subject to much uncertainty, and, if we may venture to say so, are not of sufficient importance to offer much temptation to embark in their investigation.

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XXXIII. SCHACHT ON A NEW ORGAN OF SECRETION.

UEBER EIN NEUES SECRETIONS-ORGAN IM WURZELSTOCK

NEPHRODIUM FILIX MAS.

Von Hermann Schacht.*

VON

DR. SCHACHT has noticed a new secreting organ in the rhizome of the male forn. It is in the form of a stalked clavate cell attached to the wall of the intercellular spaces, and projecting into the cavity. A green resinous matter is secreted by this organ, and settles around the outer surface of the clavate or globose cell. Usually there is only one secreting organ in each intercellular cavity, which almost fills it; sometimes two, and, in very rare cases, three are found. New secreting organs are only found in the young parts of the plant, i.e., near the vegetative cone. It would be interesting (Dr. Schacht adds) to trace the existence of this organ in other ferns, especially in the allied species of Nephrodium.

XXXIV.-KOTSCHY'S EUROPEAN AND ORIENTAL OAKS.

DIE EICHEN EUROPA'S UND DES ORIENT'S. By Theodor Kotschy. 1 vol. folio. Wien and Olmütz, 1858-1863.

THE family, or rather genus, of the Oaks, is now being studied to some purpose, especially by Continental botanists. We have already reviewed at length M. A. DeCandolle's Essay on the Variability, Distribution, and Classification of Quercus (Nat. Hist. Rev. iii. 189). His son, M. DeCandolle, has written a scientific account of the cultivation of the Cork Oak in the Forests of Algeria, wherein a large amount of French capital is embarked. In France, M. Jacques Gay, the Nestor of Parisian botanists,† has, with his usual laborious industry, investigated the history of the Cork Oak (Ann. Sc. Nat. Ser. iv., v. 6-223), or rather of the supposed two species that yield Cork in the Spanish forests; and lastly, Dr. Hooker has given us the results of his and Mr. Hanbury's personal observations on the Biblical and other Oaks of Palestine (Trans. Linn. Soc., xxxiii. 381, t. 36-38), and their relations to their western congeners.

As a fitting illustration of so important a family of plants, we have now to notice the superb work of which the title heads this

Pringsheim's Jahrbücher für wissenschaftliche Botanik, vol. 3, p. 352.

+ The announcement of M. Gay's death has been received since this article was written.

article, and which in respect of pictorial effect is perhaps the handsomest of its kind ever produced. It consists of eight imperial folio fascicles, and contains 40 plates and corresponding folios of letterpress, in German, Latin, and French, devoted to as many forms of Oak. The plates are printed in colours, at Vienna, and the effect is admirable both in an artistic and in a botanical point of view; in short, as portraits of specimens they leave nothing to be desired.

The author, Dr. Theodor Kotschy (President of the Imperial Geographical Society of Vienna), has long been attached to the Imperial Gardens and Herbarium of Vienna, as an Assistant in the Herbarium, and especially as a botanical traveller. In this capacity he has made many most important, and some very hazardous expeditions in Asia and Africa, especially Kurdistan, Syria, Palestine, Egypt, Cordofan, and Nubia, whence he has transmitted to Europe most extensive and beautifully preserved collections. He has also written a valuable book of travels, "Reise in der Cilicischen Taurus," in which the altitudinal distribution of the plants of the Taurus is laboriously and conscientiously worked out, and much other curious and useful botanical matter detailed.

The Genus Quercus, according to Kotschy, consisted in the time of Linnæus's "Species Plantarum," 1763, of only 14 species; in the "Systema" of Willdenow, published in 1805, these were augmented to 76; Sprengel, in 1820, enumerated 105; Endlicher, in 1847, had 213; and Dr. Kotschy states that the number now known amounts to 300. How far on this last point his data are accurate, and his power of judging sound, may be questioned; at any rate the reader had better reserve his judgment on this point till the end of this article.

The Oaks of Europe and the East all fall under Endlicher's subgenus Lepidobalanus, which M. Kotschy thus distributes into groups and subdivisions, primarily according to the characters of the cup:I. MICROLEPIDIUM. Scales of the cup small, imbricated, Maturation annual.

and almost all closely applied.

1. PTHARTOPHYLLUM. Leaves falling in autumn.

a. Hemeris. Pedicels long, with 1-7 acorns. Q. pedunculata, &c.

b. Robur. Pedicels short. Q. sessiliflora, &c.

c. Dascia. Leaves with stellate hairs below. Q. pubescens, &c.

2. CHIMONOPHYLLUM. Leaves maturing in winter.

a. Galliferæ. Q. Syriaca, &c.