ALTERNATE GENERATIONS. 139 



even a large number of new individuals, and it is this 

 progeny of the individuals born from eggs which grows 

 and assumes again the characters of the egg-laying indi- 

 viduals. 



There is really an essential difference between the 

 sexual reproduction of most animals and the multiplica- 

 tion of individuals in other ways. In ordinary sexual re- 

 production, every new individual arises from an egg, and, 

 by a regular succession of changes, assumes the character 

 of its parents. Now, though all species of animals re- 

 produce their kind by eggs, and though in each there is 

 at least a certain number of individuals, if not all, which 

 have sprung from eggs, this mode of reproduction is not 

 the only one observed among animals. We have already 

 seen how new individuals may originate from buds, which 

 in their turn may produce sexual individuals ; and we 

 have also seen how, by division, individuals may also 

 produce other individuals, differing from themselves quite 

 as much as the sexual buds, alluded to above, differ from 

 the individuals which produce them. There are yet still 

 other combinations in the animal kingdom. In Polyps, 

 for instance, every bud, whether it is freed from the parent 

 stock or not, grows up at once to be a new sexual indi- 

 vidual ; and in many animals which multiply by division, 

 every new individual thus produced assumes also at once 

 the characters of those born from eggs. 1 There is, finally, 

 one mode of reproduction which is peculiar to certain 

 Insects, in which several generations of fertile females 

 follow one another, before males appear again. 2 



What comprehensive views must physical agents be 



1 MILNE-EDWAKDS, Rech. anat. et logie, etc. ; Paris, 1745. OWEN, Par- 



zool. faites pendant un Voyage sur thenogenesis, etc., q. a., p. 136; com- 



les cotes de Sicile, 3 vols. 4to. fig. pare also SIEBOLD, (C. TH. E. VON.,) 



" BONNET, (On.,) Traite d'lnsecto- Wahre Parthenogenesis, q. a. p. 120. 



