10 THE ORIGIN OF LIFE 



Bacterial scum on hay infusions and on emulsions 

 of egg and water. In these latter situations 

 myriads of minute specimens may usually be found. 

 Yet among all the multitudes of Amoebae that I 

 have seen in these and other situations, multiplica- 

 tion even by simple fission has only rarely been 

 witnessed, and the formation of brood-spores never, 

 either with or without previous ' conjugation." 



The occurrence of this latter process, or of any 

 other mode of spore formation among the naked 

 Amoebae, is stated, in all the best works on " The 

 Protozoa," to be extremely rare. Calkins, for in- 

 stance (p. 96), could refer only to two doubtful 

 cases in which such a process had been seen; and 

 the extreme rarity of its occurrence is similarly 

 admitted by Cash, Marcus Hartog, and Ray 

 Lankester, who are the principal authorities on 

 this subject. 



In explanation of what I have seen and de- 

 scribed, these authorities would never admit the 

 occurrence of Heterogenesis ; they would at once 

 appeal to their facile supposition that some " in- 

 fection ' had occurred in each and every case. 

 But infection by what? By their own confession 

 any spores or germs of Amoebae that could possibly 

 infect this or that matrix are so rare as to be prac- 



