'5 and 

 'lise to 

 odies 



sphere 



h 





uiesis i 



^^gard to 



3 ink 



the iJ 



DUtio 



^' at all accoM. 



^onwgenesisj 

 1 of the m 



?ssary 



f the one 



he other. 

 ' consideration 



i> 



* 



I ,vas much W' 

 inexplicable to M^: 



to two or three e^;- 

 ^ shortly befoj . 



.nt 



;roscopf o^^i 

 a still 1-^^' 



int res"''^' 



Zffi? BEGINNINGS OF LIFE. 



539 



thes 



Hetero: 



;enesis on the part of the 

 biologist is enormous. The knowledge obtained from 

 the study of such phenomena must suffice to throw far 

 more than a glimmer of light upon some of the most 

 obscure of zoological and botanical problems. The 

 question, however, which now most naturally presses for 



solution is — Where 



At what 



grades of complexity in the animal and the vegetal 



Hetero 



? 



sional mode of origin for totally distinct specific forms! 

 So far as animals are concerned, we can even now 

 say that evidence exists tending to show that some 



lacts may bees members of every one of the groups belonging to the 



le reality ofr class Scolecida may be produced 



I 



a process of 



already descrir ' Heterogenesis. Evidence has been abundantly brought 



forward in this chapter concerning the occurrence of 



the 



Rot'ifi 



Nematoldea, Moreov 



observations have 



, already been recorded by Dr. Gros in other memoirs 

 than those to which we have alluded, tending to show- 

 that specimens of the orders AcanthocepkaU, Tcenladay 

 and Trematoda may also be produced by processes of 

 Heterogenesis j whilst I have myself very strong 



reasons for believing that one of the Turhellaria the 



strange but highly interesting Chistonotus—may also 



the filaments 



:ess of Heterogenesis taking place within 

 of Nitella. But even this is not all. 

 As I have previously stated, there are the positive 

 observations of Dr. Gros concerning similar modes of 



