On a true parthenogenesis in moths and bees, a contribution to the history of reproduction in animals

Preface

Engaged in constant efforts to trace and clear up the history of animal reproduction, as far as this is permitted to human discernment, I have been guided to a phenomenon in Insect-life which had for a long time remained obscure to me, — I refer to the power of reproduction of some female Insects which remain unfecundated, as this not only appeared to be a great mystery, but even a fact never yet firmly established, and therefore still doubtful. I always found this so-called Lucina sine concubitu treated by physiologists as a sort of curiosity ; the same examples from Insect-life, derived from the older observers, were constantly referred to as vouchers. The question, whether the fact referred to was supported upon a firm basis, remained at the same time altogether unnoticed. As every kind of statement with regard to Lucina sine concubitu was received with so little caution and without suspicion, new observations were added to the older defective notices of this kind ; but these, in the same way, appeared inadmissible as soon as they were carefully analysed.

Since the process of the fecundation of the egg has become much better understood by the recent discoveries of Newport, Keber, Bischoff, Leuckart, Meissner, and Bruch, one was compelled to say, that all the cases of Lucina sine concubitu observed in former or modern days might be founded upon delusion or error, because up to this time the knowledge of the conditions under which fecundation takes place was still extremely imperfect. Now, when the physiology of reproduction has been enriched with many exceedingly important discoveries, and by these some essential points in the act of fecundation, iv

PREFACE.

which had been previously overlooked, have been brought to light, very different claims are made upon those observations, by which it is to be decided, whether an egg which has arrived at development was or was not fecundated.

For this reason I was not to be blamed if I made my first appearance as a sceptic, and submitted this subject to an examination corresponding with the present fundamental laws of Physiology. The results of this examination, contrary to expectation, have furnished the proof 1. that a Lucina sine concubitu does exist ; and 2. that this does not merely start up here and there accidentally, as was formerly supposed, but that it occupies its perfectly definite position in nature. It is true that it still remains concealed from us, according to what laws and under what motives this remarkable mode of reproduction has obtained the place assigned to it in the history of reproduction.

In these investigations, to which I have devoted the careful study of many years, I was very readily and disinterestedly assisted by various naturalists, who, partly by providing me with the materials necessary for such investigations and observations, but partly also by communicating their own multifarious experience upon the department in question, put me in a position to obtain as wide a glance as possible over this still imperfectly explored field. I therefore regard it as my duty to express my public thanks here to Baron von Berlepsch of Seebach, MM. Bremi of Zurich, Dzierzon of Carlsmarkt, Professor F. de Filippi of Turin, Dr. Herrich-SchafFer of Ratisbon, Senator von Heyden of Frankfort a. M., M. Kollar, Director of the Imperial Cabinet at Vienna, MM. Radlkofer of Munich, Reutti of Freiburg, Dr. Rosenhauer of Erlangen, A. Schmid of Eichstadt, Steiner of Breslau, and Professor Zeller of Glogau, for the assistance which they rendered me in my investigations.

C. T. E. VON SlEBOLD.

Munich, 25th March 1856.

TRANSLATOR'S PREFACE.

Of all the discoveries which have been made of late years in the history of the reproduction of animals, none is of greater importance than that of the entrance of the spermatozoids into the ovum, which is found to be the rule not only in the Animal, but also in the Vegetable Kingdom. Nevertheless, but a few years have elapsed since the final settlement of this disputed question, and we have in the following observations of Professor Siebold a clear proof of the occurrence of phasnomena, which, if they do not invalidate the law, at least show that it is liable to some, probably to many exceptions.

Several years ago our author published some observations upon a species of Psyche, which, as he stated, propagated without copulation. He referred this singular occurrence to the same class of phaenomena as the asexual reproduction of the Aphides, the so-called Alternation of Generations ; and although it must have been evident to every one who attentively studied his paper that the circumstances of the two cases were widely different, it was impossible, in the state of our knowledge at the time, to propose any more satisfactory explanation of the phenomenon. Now, however, the whole face of affairs is changed. Von Siebold, as will be seen in the following pages, has clearly proved the existence of a sexual reproduction without fecundation, not only in the Psychidce, to which his former observations related, but also in the Bees, — in both as a regular occurrence, and as an occasional phenomenon also in the Silk-worm Moth ; the latter circumstance giving a considerable degree of probability to some even of those supposed cases which our author discusses and rejects as inadmissible in the first section of his book. For this phenomenon of reproduction by virgin females the author adopts the term Parthenogenesis, originally proposed by

VI translator's preface.

Professor Owen to express the dissimilar Digenesis or Alternation of Generations.

That the same thing occurs in other species of animals besides those upon which the author's observations have been made, there can be no doubt, and. in fact, several of these are indicated in his concluding remarks. Of some of the Entomostracous Crustacea no males have vet been detected, whilst the females of others have been observed to propagate without concourse with the male. A still more striking instance is afforded by the Gall-flies belonging to the restricted genus Cyuips. of which several species are very common in Europe, and yet amongst the thousands which have been reared from galls, not a single male has ever been seen. An oak-gall has been found in great quantities of late in Devonshire, which has attracted considerable attention from those few Entomologists in this country who trouble themselves with the study of Hvmenoptera. ' It is produced by a species of Cynips, and all the specimens, to the number of several hundreds, which have been reared, connrm the above statement as to the absence of males. Some experiments now being made by Mr. Smith of the British Museum, whose tact and power of observation so

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cited in support of the interesting and important theory developed by Von Siebold in the following pages. Amongst the Entozoa, we may also probably meet with further instances of Parthenogenesis, as their propagation, notwithstanding the great advances that have of late been made in our knowledge of its phenomena, still presents much that is enigmatical.

But it is not only in the Animal Kingdom that we meet with this phs-nomenon of ovular reproduction without impregnation : similar instances occur also amongst the Phanerogamous plants. Many years ago, Camerarius and Spallanzani asserted that the female Hemp was capable of producing fertile seed without the aid of the male pollen ; and a French botanist, M. Lecoq, has lately addressed a note to the Academy of Sciences, referring to some experiments made by him, and published in 1S27, upon the same subject. His experiments were made upon various dioecious plants, amongst which Hemp, Spinach, Mercurialis translator's preface.

vii annua, and Trinia vulgaris furnished him with fertile seeds, although every precaution was taken to isolate the plants. (See Comptes Rendus, 8th December, 1856, p. 1069.) A dioecious Euphorbiaceous plant also, the Ccelebogyne, from Australia, has produced fertile seeds in the Botanic Gardens at Kew, although only the female is known to botanists.

Interesting as this curious discovery of Von Siebold's must be to the Physiologist, there are some points connected with it which render it of the highest practical importance to the keepers of Bees. The greater part of the following pages is devoted to the consideration of the wonderful series of phenomena presented by the reproduction of those industrious Insects, and the intelligent Bee-keeper will find that by studying it he will obtain many hints, which, if properly applied in practice, may enable him not merely to study the habits of his interesting charges with much greater satisfaction than heretofore, but also, by proper management, to increase the profits derivable from his hives, — a consideration which may perhaps have more weight with many than any of a purely theoretical nature.

Although I cannot flatter myself that I have done full justice to the exceedingly happy phraseology in which Professor von Siebold has communicated his results to the world, I have endeavoured as far as lay in my power to adhere strictly to the original, so that the English reader might at least be sure of getting the true sense of the author.

The proof-sheets have been submitted to Professor Owen, who has kindly enriched them with some valuable notes, of which those relating to Hunter's views are especially interesting. The additional notes are all included between brackets.

W. S. DALLAS.

London, 20th January, 1857.

Contents

Page

Introduction 1

Elucidation of the Cases hitherto described as Parthenogenesis . . 12