FOSSILS THEIR NATURE AND INTERPRETATION. 9/ 



represent organisms, but fossils alone record for us and reveal 

 to us the actual laws of organic evolution. But the paleon- 

 tologist has ever to bear in mind that he has only the records, 

 not the living organism, for study ; and he has to look to the 

 zoology and botany of living organisms for the interpreta- 

 tion of his records. 



Living Organisms furnish Direct Evidence of Purposeful Devel- 

 opment. The zoologist finds the organism to be essentially a 

 machine accomplishing a multitude of acts, which he calls 

 functions, because every act of the organism appears to be 

 purposeful, the end seems to be more essential than the 

 means, and the organism grows to be a complex structure, 

 with a variable number of parts, each constructed with adap- 

 tation to the function to be performed. This is what is 

 found upon analysis of the living individual ; the organism is 

 already active, performing its functions, and building or con- 

 structing parts for the fuller performance of those functions, 

 or for performance of other functions. As the individual 

 organism is seen in activity, the changes it undergoes, or 

 technically its development, is seen to be definitely pur- 

 poseful. 



When it is compared with other organisms it is looking 

 forward to distinct functions to be performed in the future, 

 and when we look backward along the course of its develop- 

 ment we see it arising in the midst of a perfected individual 

 like itself, and it imitates in its development the very steps 

 taken by this earlier organism. Because of this imitation, 

 because of a repetition of what was before, we assume this 

 ancestral model to have determined the particular form, and 

 function too, of the newly arising individual. In all this 

 study we find the living organism to be incessantly changing. 

 If we make histological examinations we find every particle 

 changing, but relative integrity and solidarity of some of the 

 parts which perform definite functions is preserved. These 

 parts are called organs. These organs are the parts of the 

 machinery with which the individual works. The active, 

 living individual is thus between two forces. The ancestry 

 behind it determines its development, but the conditions into 

 which it comes determine it from before, and the product is 



