"On. 



e 



•liol 

 ^the 



tliis 

 tter 



hicli 



t , 



uite 



rrier 



lor 



tliis 

 eof 



riD2 



■1; 





.J/,'; 



Slip- 



^e- 



V 



is 



Ch. XXXVI.] EEVIVAL OF CHAEACTEES IN CEOSS-BEEEDS. 291 



most 



inheritance present to us. Bj what favourable combination 

 of circumstances can we suppose these characters, which must 

 have been Ijing latent in so many intermediate generations, 



to be tlins made again to manifest 



In some 



cases they are developed alternately in successive genera- 



tion 



s 



in others at longer intervals. 



The composition of the molecules which form the p-erm- 

 cells of animals and plants, and their mode of multipli- 

 cation and transmission from one generation to another, has 

 been a favourite subject of speculation ever since the time of 

 BufPon and Bonnet. More recentlv (18491. Professor OwAn 



Memoir 



SIS 



Mr. Herbert 



on the man- 



ner in which the atoms or physiological units composing the 

 fertilised germ of an animal or plant may unfold into orga- 

 nisms and become the means of transferring the qualifica- 

 tions of the parent to the offspring.* The new hypothesis 



Ml 



called 



manj 



Pange- 



and cannot be fully understood without reference to the 

 luminous and detailed explanations of it given by Darwin in 

 the concluding chapters of his new work.f He assumes that 

 the germ-cells of animals and plants are capable of generating 

 minute bodies, termed by him cell-gemmules, which become 



organism 



m 



uniting with others like themselves, and 



state . 



m 



may take place after the usual man 



ner of growth in all living beings, according to which enthe 

 limbs are sometimes reproduced in the lower animals after 



be developed into a perfect individual. The cell-gemmules 



form- 



b may 



many 



rudimentary 



which, though useless, may be inherited for an indefinite 



I Principles of Biology, toI. i. chaps, iv. and viii. 

 t Darwm ' On Variation,' chaps, xxxvii. and xxxviii. 



u 2 



\ ~ 



