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Show • 110 HYPOTHESIS OF THE DEVELOPMENT OF animals, the ne'v being passes through stages in which it is successively fish-like and reptile-l1ke. But t_he reserr&blancc is not to the adult fish or the adult reptile, but to the fish and reptile at a certain point in their fretal pr0· gress; this holds true ~·ith regard to t~e vascular, nerv~us, and other systems alike. It may be Illustrated by a s1m· ple diagram. The fcetus of all the fou~ _classes may _be eupposed to advance in an identical condtbon to the pmnt .1\. The fish there diverges and passes .M along a line apart, and peculiar to · ~lf, JJ its mature state at F. The reptile, ---- B Jird, and mammal, go on together to C, D --- where the reptile diverges in like man- . ~ R ner, and advances by itself to R. The ~ bird diverges at D, and goes on to B. 0 ------ F The mammal then goes fonvard in a ----- straiD"ht line to the highest point of or- A gani~ation at M. This diagram shows _ only the main ramifications; but the reader must suppose minor ones, represent the subordinate differences of orders, tribes, families, genera, &c., if he wishes to e.~dend his views to the whole varieties of being in the animal kingdom. Limiting ourselves at present to the outline afforded by this diagram, it is apparent that the only thing required for an advance from one type to another in the generative process i:s that, for example the fish embryo should not diverge at A, but go on to C before it diverges, in which case the progeny will be not a fish but a reptile. To protract the straightforward part of the gestation over a small SJJace-and from species to species the space would be small indeed-is all that is necessary. This might be done by the force of certain external conditions operating upon the parturient system. The nature of these conditions we can only conjecture, for their operation, which in the geological eras was so powc~ .. f-Jl, has in its main strength been long interrupted, and IS now perhaps only allowed to work in some of the lowest departments of the organic world, or under extraordinary casualties in some of the higher, and to these points th«=' attention of science has as yet been little directed .. But though this knowledge were never to be clearly att~1nc~, it need not nmch aflect the present argument, prov1de? 1t be satisfactorily shc~wn that there must be some such tn· fiuence within the ravq;e of natural things. I I THE VEGETABLE AND ANIMAL KINGDOMS. 111 To this conclusion it must be greatly conducive that the l::tw of organic development is still daily seen at work t0 certain effects, only somewhat short of a transition from species to species Sex we have seen to be a matter ot development There is an instance, in an humble department of the anima! world, of ~..r.rangements being made by the animals themselves for adj11sting this law to the production of a particular sex. Amongst bees, as amongst several other insect tribes, there is in each commun1ty but one true female, the queen bee, the workers being false females or neuters ; that is to say, sex is carried <>Il \n them to a. point where it is attended by sterility. The preparatory states of the queen bee occupy sixteen days those of the neuters, twenty; and those of males twentyfour. Now it is a fact, settled by innumerable observations and experiments, that the bees can so modify a worker in the larva state, that, when it emerges from the pupa, it is found to be a queen or true female. For this purpose they eniarge its ceH, make a pyramidal hollow to allow of its assuming a vertical instead of a horizontal position, keep it warmer than other larvre are kept, and feed it with a peculiar kind of food. From these sin1ple circumstances, leading to a shortening of the embryotic condition, 1·esults a creature different in form, and also in dispositions, from what would have otherwise been produced. Some of the organs possessed by the worker are here altogether wanting. We have a creature " destined to enjoy love, to burn with jealousy and anger, to be incited to vengeance, and 1:o pass her time without labor," instead of one " zealous for the good of the community, a defender of the public rights, enjoying an immunity from the stimuh.s of sexual appetite and the pains of parturition; laborious, industrious, patient, ingenious, skilful~ incessantly engaged in the nurture of the young, in collecting honey and pollen, in elaborating wax, in constructing ceHs and the like !-paying the most r pectfu1 and assiduous attention to objects which, had its ovaries been developed, it would have hated and pursued with the most vindictive fury till it had destroyed them !"* All these changes may be produced by a mere modification of the embryotic progress, which it is within the powf'r of the adult animals to effect. But it is important to observe Ctat this rnod.ification is different from working a direct "' Kirby and Spc:ce. |