PARTHENOGENESIS. 65 



His objections to the original use of it, indeed, appear to rest partly on 

 an untenable ground of etymology, partly on a misconception of Owen's 

 views, which the distinct statement given by the latter should have pre- 

 cluded. Owen, however, seems not indisposed to accept the limitation 

 proposed, and suggests the term Metagenesis, for the sum of those changes 

 which certain species undergo in the progress through successive indivi- 

 duals from the ovum to the perfect [impregnating and] egg-producing form, 

 or as it has been called the Alternation of generations. The term we have 

 enclosed in brackets seems to be redundant, and might, in fact, invalidate 

 the definition, according to the facts collected by Siebold in the little 

 volume which we are here to notice. The result of these would seem to 

 be, that the animal development from a perfect egg may take place without 

 impregnation, 1° exceptionally ; — 2° normally, the law prevailing either 

 partially, as subservient to definite purposes in the social economy of the 

 species, or cyclically through a limited number of successive generations, or 

 permanently and universally in regard to certain groups. The evidences 

 which Siebold has here collected are not absolutely new, but they had partly 

 been overlooked,* partly they seemed to demand that closer investigation, 

 anatomical and historical, with which he has here supplied us, so that we are 

 now in a condition to recognise a law of generation, of which the higher 

 forms of animal life in the vertebrate classes have afforded no unequivocal 

 example. 



Various statements have appeared from time to time of fertile eggs 

 being laid by female Lepidoptera secluded from all access of the male. In 

 some of these cases the progeny has been reared to the perfect state, and 

 the experiment has even been continued through more than one generation 

 in succession. Indeed, the published instances are so many, and the autho- 

 rities so respectable, that the rather sceptical criticism which Siebold has 

 applied to them might appear overstrained. It has led him, however, to 

 institute fresh experiments, guarded with all the precautions the assurance 

 of which he misses in the previous documents, and these have obliged him 

 to admit the fact, in respect to the common silk worm, that the female 

 moth is capable of laying fertile eggs without impregnation. The propor- 

 tion of the eggs, however, which are capable of development in this case 

 is small, and, generally, it would appear that a natural limit is set in this 

 way to the propagation of the species in any but the ordinary mode of 

 generation. A very peculiar mode of limitation is indicated by an experi- 

 ment of Carlier, which Lacordaire has recorded in his Introduction. Three 

 successive generations of Liparis dispar were produced by secluded 



