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SCIENCE 



[N. S. Vol. XXVII. No. 685 



mental method is being largely applied in 

 biology as in the physical sciences. 



The historical and descriptive study of 

 biology has been gradually giving place to 

 esperiment. The zoologist is no longer 

 content with systematic work, with the 

 naming and classifying of species and 

 genera, but he seeks to understand the 

 chemical and physical changes that occur 

 in growth, development, old age, death, 

 etc. ; or, in other words, he would know the 

 cause or causes of these phenomena. He 

 would understand the reason for things 

 that occur during life, and with that end 

 in view he turns to the experimental 

 method, just as in physics and chemistry 

 experimental or analytical study is made 

 use of in the solving of problems that 

 pertain to these sciences. 



In botany, attention is being more and 

 more directed to the study of plant physi- 

 ology, with its chemical and physical prob- 

 lems. It is not enough to know that some 

 species of fungi, for example, become 

 black at a certain stage of their growth, 

 but we need the explanation of the cause. 

 The enzyme is to be detected and isolated, 

 and the substance or substances upon 

 which it acts identified. So, too, the many 

 phenomena connected with the growth, 

 nutrition and pathology of plants interest 

 us, but knowledge of what is actually 

 occurring can only be had by application 

 of chemical methods. Systemic study of 

 plants and animals will always be im- 

 portant, but if we are to have adequate 

 explanation of the hundred and one phe- 

 nomena characteristic of living forms we 

 must turn our attention to experimental 

 methods, as is being so largely done at the 

 present time throughout the biological 

 world, with due regard also to possible 

 chemical transformations and reactions, 

 that may be symbolical of broader changes 

 in function and structure. 



Descriptive embryology may tell us 

 much regarding development, may show 

 us the many different stages through which 

 the egg, after fertilization, passes on its 

 way to the full-fledged organism, but we 

 gain thereby little or no insight into the 

 causes that are operating to accomplish the 

 ultimate end. We may well conjecture 

 that in fertilization the spermatozoon 

 brings in some chemical elements that con- 

 stitute the exciting cause of cell division. 

 Assuming such to be the case, we may ask 

 whether it is a ferment substance of the 

 ordinary enzyme type, or whether sub- 

 stances of a totally different character are 

 involved. The answer to this question, 

 however, does not concern us now ; but that 

 such a question is pertinent clearly sug- 

 gests how the cause of cell cleavage may 

 possibly be sought for in chemical or 

 physico-chemical reactions incited by the 

 admixture of germ and sperm substance. 



It is well understood to-day that all the 

 phenomena of life are to be explained on 

 the basis of chemical and physical laws, 

 and it is partly because of a clear recogni- 

 tion of this fact that biological chemistry 

 has finally attained the eminence it has now 

 reached as a division of biology; a branch 

 of study that promises much in the ulti- 

 mate explanation of many of the most 

 intricate of the present-day problems of 

 life. There is another reason why bio- 

 logical chemistry has shown such remark- 

 able development during the past decades, 

 and that is because of the direct aid it has 

 furnished, and still promises to furnish, to 

 physiology and to both experimental and 

 practical medicine. Physiology as an in- 

 dependent science, having to do with the 

 study of function, has grown in keeping 

 with the increasing demand for wider 

 knowledge of the processes of life, and 

 this has led quite naturally to a broader 

 recognition of the importance of the chem- 



