CHAPTER XII 



DOES SILICON, EITHER WHOLLY OR IN PART, ENTER 

 IN THE PLACE OF CARBON INTO THE COM- 

 POSITION OF THE PROTOPLASM OF THE ORGAN- 

 ISMS FOUND IN THE TUBES? 



THE question which stands at the head of this 

 section cannot at present be answered. Still, it 

 seems necessary to call attention to it for the 

 following reasons. 



It is now well known, as Professor Emerson 

 Reynolds says, 1 that there are 



a considerable number of silicon compounds, includ- 

 ing nitrogen, which resemble those of carbon with 

 nitrogen, both in composition and in the general na- 

 ture of the changes in which they can take part. 

 Some of these carbon analogues are closely related to 

 those which are concerned in building up the organ- 

 ised structures of plants and animals. ... In view 

 of our newer knowledge, there is, therefore, nothing 

 very far-fetched in supposing that, under suitable 

 conditions, a plant or an animal organism may be 



1 Nature, August 12, 1909, p. 207. 



in 



