THE ACTIVITIES OF THE ORGANISM 107 



water in a flask to see what resembles surprisingly 

 the arrangement of certain kinds of connective tissues 

 in the organism. Obviously these artificial phenomena 

 have nothing to do with living substance. 



Yet if we grind up a living muscle with some sand 

 in a mortar we do destroy something. The muscle 

 could be made to contract, but after disintegration this 

 power is lost. We have certainly destroyed a structure, 

 or mechanism, of some kind. But, again, the paste of 

 muscle substance and sand still possesses some kind 

 of vital activity, for with certain precautions it can be 

 made to exhibit many of the phenomena of enzyme 

 activity displayed by the intact muscle fibres, or even 

 the entire organism. Mechanical disintegration, there- 

 fore, abolishes some of the activities of the organism, 

 but not all of them. If, however, we heat the muscle 

 paste above a certain temperature, the residue of vital 

 phenomena exhibited by it are irreversibly removed, 

 so that heating destroys the mechanism. This we can 

 hardly imagine to be the case (within ordinary limits 

 of temperature at least) \vith a physical mechanism, 

 but again a mechanism which is partly chemical might 

 be so destroyed. We see, then, that protoplasm 

 possesses a mechanical structure, but that all of its 

 vital activities do not necessarily depend on this 

 structure. The full manifestation of these activities 

 depends on the protoplasmic substance possessing a 

 certain volume or mass, and also on a certain chemical 

 structure. 



If living protoplasm has a structure, and is not 

 simply a mixture of chemical compounds, what is it 

 then ? Two or three physico-chemical concepts are 

 at the present time very much in evidence in this 

 connection. When the substances known as colloids 

 were fully investigated by the chemists, much attention 



