SPECIALIZATION AND ORGANIZATION. 21 



new system of specializations and integrations, with 

 correspondingly high grades of life. The final stage of 

 each order of units represents a complete individuality, 

 which cannot be divided without destruction. So we 

 advance from certain " physiological units " to the 

 indivisible cell, from the cell to the indivisible organism 

 composed of cells, from the highest units here to those 

 of the social order. 



It is unnecessary to enlarge further upon these facts. 

 It remains only to point out their bearing in relation 

 to the biological sciences. 



The days when naturalists could presume to take all 

 nature for a subject of study and meditation are a long 

 way behind us. The cosmogonists of olden times en- 

 gaged single-handed with all the mysteries of the 

 universe. We honor them for their heroic efforts, 

 ineffective as they were from misdirection. At the 

 expense of centuries of baffled efforts, the lesson began 

 at last to be learned, that division of the problem 

 facilitates progress. That a knowledge of the whole 

 presupposes a knowledge of the parts, was a simple 

 enough fact ; but it took a long time to turn it into 

 practice. 



Division of labor in the sciences, as elsewhere, has 

 been a thing of slow growth, self-originating, self-per- 

 petuating, and self-regulating. It has taken possession 

 of the biological sciences, and presides over their 

 onward march, just as it determines and directs social 

 and industrial progress. It is simply an economical 

 principle, the growth of which began with, advances 

 with, and will always have its limitations in, an actual 

 need — the need of concentrated attention. This need 



