192 PHYSICAL STATE OF PEOTOPLASM. 



At the same time, sufficient mobility is given to facili- 

 tate those rapid metabolic changes, and the access of 

 pabulum and the removal of products which are essen- 

 tial to vital action. For this reason, also, the living 

 matter can never exist as a rigid structure of any 

 kind. This peculiar semi-solid state is called the state 

 of imbibition, and is so remarkable that Schwann 

 gives it a prominent place in the process of building 

 up the organic structures. In fact he is inclined to 

 the opinion that " organisms are nothing but the form 

 under which substances capable of imbibition crystal- 

 lize" (215). And Hackel, following Schwann, suggests 

 that the imbibition state should be considered a fourth 

 physical state of matter,* as it is to be distinguished 

 from the mere humidation of aggregations like sand- 

 stone ; and the fact that crystalline bodies are incapable 

 of imbibition is one reason why they are incapable of 

 living action. He exalts this faculty to the skies as a 

 main factor in the production of vital phenomena, by 

 bringing the pabulum into the interior of the mass, 

 contrary to what happens in crystals. But in reality 

 it explains nothing at all, for when the nutriment* has 

 got into the interstices of the protoplasm the^diffi- 

 culty of explaining the peculiar changes it undergoes 

 there, only begins. In fact this is not a distinctively 

 vital state at all, but belongs to ordinary colloids. 

 But there is a difference between the physical state of 

 the colloids and that of the living matter, for the 

 former are, in many instances, capable of true solution, 

 e.g.j gelatin, which no living matter is. The tearing 

 asunder of the molecular groups by the adhesive force 



* " G-enerelle Morphologic," i. p. 124. 



