LIFE. 13 



The vital functions of organisms are : — 



Primary. — i. Alimentation. 



2. Movement. 



3. Sensation. 



4. Excretion (and Secretion); 



Secondary. — I . Growth. 



2. Reproduction. 



It cannot be too much Insisted upon that these vital 

 functions are all exhibited by all living organisms from 

 highest to lowest. 



If the secret of vital phenomena ever be revealed to the 

 future scientific investigator, the steps from Amoeba to man 

 will appear as a mere nothing compared to the immeasurable 

 difference between living protoplasm and its non-living con- 

 stituent proteids. 



We know life only by its effects, not in itself, and 

 the student should ever bear in mind that just as the 

 physicist has to assume the fundamental conceptions of 

 matter and motion, so the zoologist, the biologist and the 

 physiologist have to start with the assumption of hfe and its 

 vital phenomena. The attempt to explain these premises 

 in each case is mere speculation. 



