138 THE ORIGIN OF LIFE 



fluid condition of the substance undergoing change, 

 while, on the other hand, the idea of a definite form 

 involuntarily suggests a fixed position of the particles 

 of matter of which the organism is composed. This 

 difl&culty, however, is merely superficial and vanishes 

 as soon as we examine the two seemingly irre- 

 concilable facts. A fluid substance is certainly a 

 requisite of metabolism. In the words of the an- 

 cient alchemists, cS-pora non agunt nisi humida. 

 Only gases or dissolved matter can enter into the 

 chemical relations required in the metabolism of an 

 organism." 



Upon this point recent physical and chemical work 

 seems to show that that fluidity of state can, to a 

 certain extent, exist even in solid bodies, and that 

 metabolism is in a more minute degree a pheno- 

 menon which can take place even in solids. We 

 shall see in a later chapter that there is considerable 

 evidence of such metabolism in phosphorescent and 

 other solid bodies. 



Max Verworn, however, does admit that there can 

 be no doubt that protoplasm, which, as he thinks, is 

 essentially a fluid, does contain some more solid and 

 firm elements in it ; that it is a compound of substances 

 of various constituents, and that those who hold the 

 opposite view base it solely on the examination of 

 dead and preserved objects. It is, however, held by 

 many, as he admits, that the protoplasm and the 

 nucleus is a sponge-like network or a thread-like 

 structure, composed of numberless fibres. He then 

 asks, " What are we to consider as actually living in 



