62 THE STORY OF THE LIVING MACHINE. 



like that of our supposed supramundane observer 

 when he first found the human being that brought 

 into connection the widely different cities in the 

 various parts of the world. 



Schwann and his immediate followers, while 

 recognizing that the bodies of animals and plants 

 were composed of cells, were at a loss to explain 

 how these cells arose. The belief held at first 

 was that there existed in the bodies of animals 

 and plants a structureless substance which formed 

 the basis out of which the cells develop, in some- 

 what the same way that crystals arise from a 

 mother liquid. This supposed substance Schwann 

 called the cytoblastema, and he thought it existed 

 between the cells or sometimes within them. For 

 example, the fluid part of the blood is the cyto- 

 blastema, the blood corpuscles being the cells. 

 From this structureless fluid the cells were sup- 

 posed to arise by a process akin to crystallization. 

 To be sure, the cells grow in a manner very differ- 

 ent from that of a crystal. A crystal always grows 

 by layers being added upon its outside, while the 

 cells grow by additions within its body. But 

 this was a minor detail, the essential point being 

 that from a structureless liquid containing proper 

 materials the organized cell separated itself. 



This idea of the cytoblastema was early thrown 

 into suspicion, and almost at the time of the an- 

 nouncement of the cell doctrine certain micro- 

 scopists made the claim that these cells did not 

 come from any structureless medium, but by divi- 

 sion from other cells like themselves. This claim, 

 and its demonstration, was of even greater im- 

 portance than the discovery of the cells. For 

 a number of years, however, the matter was in 

 dispute, evidence being collected which about 



