420 THE BEGINNINGS OF LIFE. 



Desmids, Diatoms, or algoid corpuscles may be due to 

 the growth of almost invisible germs derived from 

 previously-existing similar organisms, one is bound to 

 state on the other hand that such germs are never 

 recognizable in the situations upon which the out- 

 growths subsequently appear, and that the postulation 

 of their existence is an assumption based upon no inde- 

 pendent evidence. 



What is at present known concerning the modes of 

 reproduction of Desmids and Diatoms 1 , is wholly inade- 

 quate to account for their sudden appearance in great 

 numbers, in situations where they did not previously 

 exist. And in the face of the actual transformations 

 which have now been witnessed by independent ob- 

 servers, whereby algoid or euglenian corpuscles are bodily 

 converted into Diatoms or Desmids, it is rendered all 

 the more probable that the bud-like method of origin is 

 as independent of pre-existing Desmid or Diatom as it 

 seems to be. But concerning the transformations of 

 pre-existing corpuscles of a different nature into such 

 bodies, we shall have more to say in the next chapter. 



On other occasions certain of the Protococcus-like 

 corpuscles which are so frequently given off from many 

 Algae may, instead of multiplying after the fashion of 

 Confervas, increase in size and gradually exhibit an 

 animal-like activity, whilst still retaining their green 

 colour. They thus become converted into Astasiae and 



1 See Pritchard's ' Infusoria,' 4th ed., pp. n and 58. 



