4 ANIMAL LIFE 



of a very complex chemical and physical constitution. Its 

 chemical structure is so complex that no chemist has yet 

 been able to analyze it, and as the further the attempts at 

 analysis reach the more complex and baffling the substance 

 is found to be, it is not improbable that it may never be 

 analyzed. It is a compound of numerous substances, some 

 of these composing substances being themselves extremely 

 complex. The most important thing we know about the 

 chemical constitution of protoplasm is that there are al- 

 ways present in it certain complex albuminous substances 

 which are never found in inorganic bodies. It is on the 

 presence of these albuminous substances that the power of 

 performing the processes of life depends. Protoplasm is the 

 primitive basic life substance, but it is the presence of these 

 complex albuminous compounds that makes protoplasm the 

 life substance. A student of protoplasm and the funda- 

 mental life processes, Dr. Davenport, has said, "Just as 

 the geologist is forced by the facts to assume a vast but 

 not infinite time for earth building, so the biologist has to 

 recognize an almost unlimited complexity in the constitu- 

 tion of the protoplasm." * 



* The physical structure of protoplasm has been much studied, 

 but even with the improved microscopes and other instruments neces- 

 sary for the study of minute structure, naturalists are still very far 

 from understanding the physical constitution of this substance. While 

 the appearance of protoplasm under the microscope is pretty generally 

 agreed on among naturalists, the interpretation of the kind of structure 

 which is indicated by this appearance is not at all well agreed on. 

 Protoplasm appears as a mesh work composed of fine granules sus- 

 pended in a clearer substance, the spaces of the mesh work being com- 

 posed of a third still clearer substance. Some naturalists believe, from 

 this appearance, that protoplasm is composed of a clear viscous stib- 

 tance, in which are imbedded many fine granules of denser substance, 

 and numerous large globules of a clearer, more liquid substance. Other 

 naturalists believe that the fine spots which appear to be granules are 

 simply cross sections of fine threads of dense protoplasm which lie 

 coiled and tangled in the thinner, clearer protoplasm. And, finally, 



