IOWA ACADEMY OF SCIENCES. 31 



The material equipment of the chemist is not only exten- 

 sive but very special, yet most of his aids of the more 

 general application were first employed by the physicist or 

 came from his laboratory. Chemistry recognizes its rela- 

 tion to physics with characteristic clearness, and a large 

 department of the science is given the name of chemical 

 physics or physical chemistry. 



The biological sciences form a group by themselves, and 

 stand prominently contrasted with those so far passed in 

 rapid review. There are, no doubt, great and organic dif- 

 ferences between the biological and the physical sciences. 

 But their general differences are often more purely apparent 

 than real. Classification is generally a distinguishing fea- 

 ture of these, and this is their oldest inheritance, except 

 perhaps, observation, that fundamental and most ancient 

 process in all science study. Classification, which, of course, 

 rests upon well-nigh endless comparison, is a feature more 

 strongly in evidence in some of these branches than others; 

 but it appears to the physicist that this is their distinguish- 

 ing characteristic, as measurement is that of the physical 

 branches. This does not imply that the one group does 

 not employ measurement nor the other classification. It 

 is simply intended to convey the idea of the general feature 

 which is most accentuated in each group. When this is 

 said, the essential difference has perhaps been stated. But 

 these sciences employ more and more of experimentation 

 and measurement, and their great discoveries are worked 

 out in the laboratory; and of some of them this is as true as 

 it is of physics and chemistry. Bacteriology is a laboratory 

 product; and morphological inquiry is prosecuted by the 

 most delicate and searching laboratory means. 



But without the appliances which the chemist and especi- 

 ally the physicist have developed and elaborated for their 

 own use, the biologists would practically lack the imple- 

 ments of their occupation. Their methods are largely 

 identical with those of the former, but are more restricted 

 and special in any given case. The criteria of evidence 

 are the same as in the physical sciences; but in many cases, 



