tions on a Dipterous insect which produces young in a manner altogether unusual, and very extraordinary.

Not only are the young developed in the larva, but they arise. long before the appearance of ovaries, and are developed at the expense of the fatty tissue.

It is difficult to resist the impression that Professor Wagner has mistaken parasitism for parthenogenesis; however, if his description is correct, his inference seems necessarily to follow. Moreover, his attention has been particularly directed to this point, and though he was himself disposed at first to regard the embryos as parasites, he found himself compelled to abandon this hypothesis, for the following

reasons:

1. It is almost impossible to believe that the whole organisation of a parasite should agree with that of the insect in which it lives.

2. Parasites lay their eggs at one time, and the young would therefore be of approximately the same age; whereas, in this case, the dipterous larvæ contained young ones in the most different stages of development.

3. Parasitism is exceptional; these Dipterous larvæ at a certain age all contained young ones.

4. The size of an egg is constant; on the contrary, the bodies from which the secondary larvæ were produced, increased greatly in size.

5. The outer shell of these supposed eggs served as a protection to the young larvæ until they were ready to quit their mother.

6. Professor Wagner has watched the whole development of the young larvae, and satisfied himself that they took their origin in an alteration of the adipose tissue.

7. In the larvae of the second generation, again, other larvæ are produced in a similar manner.

These are the reasons which have induced Professor Wagner, after much hesitation, to regard this curious case as a form, not of parasitism, but of Agamogenesis.

manner.

The development of the embryos takes place in the following In young larvæ the adipose tissue offers no special peculiarities, but after a while small opaque spots appear in it; each spot consists of a mass of granular matter enveloped in a delicate skin, which also includes some fatty globules. The whole corpus adiposum falls gradually, though generally not all at once, into embryonic masses of this kind. These embryonic masses are at first round or

elliptic. Gradually the fatty globules disappear, and are replaced by a granular fluid. In the following stage of development the whole contents of the embryonal masses change into nucleated cells, which first form themselves round the periphery. At the same time the embryonal mass elongates itself considerably, and assumes the form of an elongated ellipse, in the centre of which the production of yolk takes place. Professor Wagner describes as "yolk" a mass of fatty globules, mixed with fine granules, but it does not appear from his description in what manner this production of yolk takes place. The yolk appears at first in the centre, but gradually spreads outwards until it occupies the whole embryonal mass. He assumes that at this stage a process of yolk-division takes place, because he has found some embryos in which the yolk-mass was divided into a number of six-sided masses, but he has never observed the process of division itself, and we know that yolk-division, of this kind at least, is not usual among insects.

However, the whole process of embryonic development seems, from the description given by Professor Wagner to be very abnormal, since he says that the embryo arises in the centre, and not at the outside of the yolk. Gradually, however, the embryo comes to the surface, and appropriates the whole mass of yolk. When this phase of development is attained, the mother-larva shows little sign of life. She can no longer move about, the heart scarcely beats, and the daughter-larvæ occupy so much of her body that the internal organs can with difficulty be perceived.

The whole development of the larvae occupies 8-10 days; after which two or three days more elapse before they leave the mother. During this period they change their skin, and then, quitting the old embryonal covering, wander about freely in the body of the motherlarva. Although the adipose tissue breaks up into numerous embryonal masses, only a few, generally from 7 to 9, come to maturity, the others apparently being absorbed. He noticed one case in which the mother-larva contained only a single young one. In from three to five days the development of the third generation commences.

It is much to be regretted that Professor Wagner has not yet succeeded in obtaining the imago, or perfect insect, and cannot therefore determine the species, or even the genus, to which these interesting larvæ belong, but, in the opinion of Professor Siebold, they are probably a species of Cecidomyia.

- Although these observations seem to have been made with care,

and appear to justify the inference drawn from them by Professor Wagner, still the facts are of a character so extraordinary, that we shall be very glad to see them confirmed by other entomologists.

XXXI.-THE FRUCTIFCATION OF THE ASCOMYCETE.

ÜBER DIE FRUCHTENTWICKELUNG DER ASCOMYCETEN EINE PFLANZEN PHYSIOLOGISCHE UNTERSUCHUNG. Von Dr. A. De Bary. Leipzig, 1863.

THIS essay was written for presentation at the festival of the 100th anniversary of the Senckenberg Institute. Besides a number of observations upon the development of the asci and sporidia of several species of Fungi, it contains an attempt to throw some light upon the dark problem of their sexuality; but we cannot say that either the facts adduced or the arguments drawn from them are very convincing. Dr. De Bary traces the origin of the perithecium of Erysiphe cichoracearum DC. from its earliest state up to the formation of the single ascus and spores. In this process he notices two cells as being always present and visible from the earliest period, one of which he calls the "Ei-zelle," and the other the " Antheridium." The former afterwards divides, and the ascus is the result of this division. Dr. De Bary admits that the evidence of the sexuality of these organs is not strong. "However (he says) it is certain that the cell, "by the division of which the ascus and its coating are formed, only "develops itself when it has been in contact and therefore probably "in some sort of intercommunication with, the antheridium; which "latter organ is never wanting, is always of the same form and size; " and originates in the same manner." He adduces the Phænogams as showing that impregnation may take place by simple contact, and concludes that it may be assumed as very probable that the "Ei-zelle" is impregnated by the antheridium, and that the perithecium of Erysiphe (excepting the outer wall) is the product of sexual impregnation. Considering the mass of evidence, theoretical and practical, by which the nature of phænogamic embryology has been proved, it is going a long way to suggest the existence of a similar process in Erysiphe from a few novel isolated observations, especially when it is considered that in all Cryptogams in which sexuality has been satisfactorily estab lished, the presence of spermatozoa is indispensable to impregnation.

The author notices some peculiar cells which occur at an early period in the growth of Peziza confluens P., but seems to have formed no definite opinion as to their nature. He traces the formation of the paraphyses and asci, and concludes that the latter are certainly asexual on the ground that he could find no proof of their impregnation; and especially that he could never see any intimate connexion between the asci and the paraphyses. It is difficult to reconcile this reasoning with the argument in the case of Erysiphe, where simple contact is assumed to be sufficient for impregnation.

The observations on the development of asci and sporidia, to which we have before alluded, do not for the most part call for any special remarks. We may mention, however, that Dr. De Bary notices in the contents of the asci two substances, which he calls respectively Protoplasma and Epiplasma. The latter is characterised by high refractive power, its peculiarly homogeneous consistence, and especially by its becoming first of a brown-red, and ultimately of a brown-violet colour under the action of a weak aqueous solution of odine. In other respects the epiplasm is said to be of the same nature as protoplasm generally; and the author adds that it can hardly be doubted that, like the latter, it is a mixture of different substances.

There are two questions discussed in this work in which Dr. De Bary's views are in conflict with Dr. Hofmeister. The first relates to the origin of the sporidia in Tuber; and the second to the supposed sexual organs in the same genus. The question whether the sporidia originate within the protoplasm or the epiplasm will not perhaps be thought of much importance; at all events, not until more is known of the essential difference between these two substances. We think, however, that it is highly improbable that so careful an observer as Dr. Hofmeister, should (as Dr. De Bary supposes) in the first place have misunderstood the contents of the protoplasmic cavity, and should then have mixed up a number of irregular and regular appearances so as to form one developmental

series.

The question with regard to the sexual organs in Tuber is of more importance. Hofmeister noticed that the terminal cell of the delicate threads which surround the ascus becomes firmly united to the outer membrane of the ascus itself. At the point of junction, and sometimes at other points also, he observed a depression (tüpfel) in the membrane of the ascus, and he suggested the possi

bility of the terminal cell being in fact an antheridium. Dr. De Bary's doubts as to the sexual nature of the threads may be valid; but his reasons appear to us quite insufficient. He objects that

it is impossible, from the nature of the tissue, to prove that the asci and the surrounding filaments bear any constant relation to one another.

If (as we understand him) Dr. De Bary means that the difficulties of manipulation are insuperable, several of his own writings (including the present work) would be a standing protest against the validity of such an objection. The difficulty of observing the conjugation of the cells in Tuber would be slight in comparison with that of following out the formation of the perithecia in Eurotium, of tracing the ascigerous tissue of Agaricus malleus, of dissecting the filaments in Nyctalis, or of watching the growth of the enveloping cells of the perithecia in Erysiphe. The present essay has somewhat the appearance of having been brought forward a little prematurely, perhaps from a desire to do honour to the Senckenberg Institute. We hope that Dr. De Bary may be induced to review some of the conclusions at which he has arrived, and give us the results of his more mature consideration.

XXXII. -THE MORPHOLOGY OF SALVINIA.

ZUR MORPHOLOGIE DER Salvinia natans. Von N. Pringsheim. Jahrb. f. wiss. Bot. Vol. iii. No. 3.

THIS paper the author divides into two sections, the first of which relates to the growth of the shoots, and the arrangement of the leaves, especially the formation of the terminal vegetative cone (Vegetationskegel) and the origin of the leaves; while the second section treats of the structure and formation of the sexual organs, including the spermatozoa and the archegonial canal, as well as the development of the embryo-rudiment, especially with regard to the origin of the vegetative cone and the primary lateral organs of the embryo.

It would be impossible to enter into the minutiae of the author's first section, as they could not be made intelligible without a reference to figures. We may state, however, that Dr. Pringsheim has arrived at the conclusion that the shoots of Salvinia terminate with a continuously-developing vegetative cone, having a manifest