PARTHENOGENESIS IN BEES.

Lyttelton Times, Volume VIII, Issue 531, 5 December 1857, Page 3

PARTHENOGENESIS IN BEES.

(From the Westminister ffevieio.J Professor Yon Siebold lias recently made public the results of a series of researches on Insect reproduction, on which he has been engaged for a considerable time. The term Parthenogenesis was devised some years ago by Professor Owen, to designate a class of phenomena to which attention had been previously drawn by Professor Steenstrup's work on the " Alternation of Generations." The Parthenogenesis of Professor Siebold differs from the Parthenogenesis of Professor Owen in this; that whereas the latter is in very essence a sexual,the former consists in the deposition of fertile ova by true virgin females, that is by individuals whose complete development renders them fully competent to perform the sexual act in the ordinary way, but which are kept from doing so by seclusion from the male. That such an occurrence occasionally takes place among insects of various kinds, has been frequently stated upon what seemed to be adequate authority ; but a careful scrutiny into the conditions of the best authenticated cases left' Professor Siebold in doubt whether any of them really justified the affirmation ; and he therefore determined to examine the question for himself. The result of his researches is, that he has established this to be the ordinary mode of reproduction among certain species—to say the laast— of a tribe of moths termed P&ychidce, ; which are. allied to the Tmcklce (or clothes' I. moths); whilst it occasionally happens in : the silkworm moth, and, strange to say, forms part of the regular reproductive process among* bees.- The caterpillars of the Psychidas form for themselves very curious cases of various materials, some being* composed of particles of earth, glued together in the shape of a small snail-shell. When .aboutHq:pass into the pupa state, they oc.cupy the outer part of this case, and envelope -themselves in a silken cocoon which closes its aperture..'Here they undergQ: their transformation, first into'the''pupa,: and then into the perfect moth; and that; these moths are almost always female^ \ appears from the statement of Siebold, that' having examined a Hundred and fifty pupa:! within seven years, he has never found a j single male. Though kept in such perfect] ' seclusion that no male can possibly, have) . aQGess [to *hem,4lie.mQtlis vyiil still producej ■ 'eggs,; which' --they deposit. in the emjtfy:

pupa-case that remains behind in the cater-pillar-sac ; and these eggs are soon hatched and give birth to caterpillars. Whether these, when arrived at maturity, could produce fertile eggs by the same parthenogenetic process, lias not yet been ascertained. With regard to the Silkworm, it has been ascertained by careful experiments, that female moths, completely secluded, immediately on their emersion from the cocoon, will often lay eggs; and that these . eggs will give birth to larvae, which are ' metamorphosed in due time into moths.;. But, as far as can- be predicated from the: • results hitherto obtained, the eggs vyjiich the females of these moths may produce under like circumstances are not fertile. The case of the Hive-bee, however, is most curious of all. Every one knows that each community includes a single queen, who is the only /perfect female, and by whom alone eggs are ordinarily produced —numerous drones, or males,—and a vast' number of workers, which are commonly termed neuters. All these are evolved from eggs,which are deposited in waxen cells of different kinds. Those for the drones and for the workers are both of the ordi- ■. nary hexagonal build; but the drone-cells are considerably larger than the workercells. The royal cell, however, is : constructed on a very different plan; • | and the food with which the royal ■ grub is nourished is quite .unlike the ordinary bee bread. Yet the. experiments of Huber, abundantly confirmed by subsequent inquirers, have demonstrated that a worker-grub, not too • far advanced in its development, if transferred to a royal cell, and fed on the peculiar nutriment of the queen larvas, becomes developed into a perfect queen; whence it appears that the workers are really undeveloped females, a conclusion quite justified, by a careful scrutiny into their organization. Until recently, however, no doubt has been felt as to the fact, that all the fertile eggs laid by the queen bee, whether workers, drone?, or queens be developed from them, are;, the results of sexual congress between ihe parent queen and one of the drones. This congress is known to occur, not within the hive, but in the air, during' what has been termed the nuptial flight; anil the practised beekeeper . has no difficulty in determining whether it has or has not taken place. As in insects generally, a single congress serves for-the fertilization of .a multitude of eg'g-s successively developed, the ferti- . lizing fluid being stored up in a receptacle opening upon the oviduct, and thus each egg is impregnated as it descends. From time to time,, however, observant bee- . keepers hare stated that queens, whose wings are so imperfect that they cannot leave the live for the nuptial flight, have nevertheless laid fertile eg*gs, all these eggs being drane-eg'gs; and further, that workers have occasionally laid fertile eggs, which, as before, are always drone-eggs. As there was strong reason to believe that in neither., case iovld sexual congress have taken .-' place, there seemed to be a probability that these drone-eggs are the result of a paichenogenetic procreation, analogous to that of the psyche and bombyx ; and Professor Siebold, after carefully examining' into the question for himself, has arrived \ • ,at the conclusion that such is assuredly tlie case. But since the queen impregnated in tlie ordinary way also lays drone-eggs, and this in the midst of laying" worker- ' eggs,. the question next arises whether '■ some drone-eggs are fertilized by the male fluid, though others are not so fertilized, or whether the drone eggs of an impreg- ! nated female are in any way prevented from receiving it's influence. This problem . ; could only be solved by careful microscopic examination of the eggs immediately upon their being- laid; and the observations of Professor Siebold.(whose high reputation as a trustworthy observer is a sufficient guarantee of the credibility of his assertions) enable him to affirm, that whereas the fertilization of the worker-eggs by the male fluid can be recognized by the presence of spermatozoa upon each of them, no spermatozoa are detectable upon the drone-eggs ; so that the drone-eggs, whether proceeding from virgin or from impregnated queens, are always deposited without any fecundation from the male. This is the most marvellous doctrine; and, if it should prove-correct, it introduces quite a new element into the physiology of ■ •generation. It is not the least curious part of the history, that the very same eggs, so far as can be made out, may give origin either to males or to females, the difference of sex being determined by tlie presence or absence of tlie male fecundating.influence {.and.it; tends rather to subvert the usual^uotions^. oi '..male superiority, to

find that in this case the complete performance of the .generative act gives birth to females, and that the males originate in what seems.a lower form of the process. The whole matter, however, requires a most rigorous and repeated investigation -before the facts of the case can be regarded as proved, since the sources of fallacy aTe very numerous, and it is not a little curious,, that Dzierzon, the originator of the theory of the parthenogenetic production of drones, should have afterwards retracted it, at the very time that Professor Siebold's investigations were affording it new and powerful support. We commend the inquiry to intelligent beekeepers throughout the country as one the prosecution of which will -do good service to science; for if the whole doctrine be erroneous, the sooner it is disproved the "better:; whilst if it be founded in truth, its confirmation will lead to analogous investigations elsewhere.