, FOREWORD 11 



tically unknown. Surely the existence and action 

 of such bodies ought not to be postulated gratui- 

 tously and independently of all evidence. More- 

 over, in many of the cases the whole substance of 

 the resting-spore, the Euglena or the Rotifer's 

 egg, may be seen to have undergone simultaneous 

 segmentation into Amcebce. 



What has just been said concerning the hetero- 

 genetic origin of Amoebae might be repeated in 

 very similar terms in regard to some Ciliated In- 

 fusoria, except that such an origin for them has 

 been observed more rarely. The instances are, 

 however, quite as impossible of any real explana- 

 tion otherwise than by heterogenesis. Germs of 

 Ciliates are similarly unknown which could be 

 supposed to have " infected ' the great encysted 

 Amoeba? or the great Rotifer's eggs, which at times 

 segment, also without any remainders, into spe- 

 cimens of this or that particular kind of Ciliate, 

 as I have seen and have illustrated by photographs 

 in the work above mentioned. 



But the notion of the possibility of Hetero- 

 genesis is generally repudiated, and is scarcely 

 ever likely to find favour except with those who 

 believe that living matter is still constantly com- 

 ing into existence de novo. My facts and views 



