5 94 THE HISTORY OF BIOLOGY 



H. O. G. Rosenberg, of Stockholm, who has investigated the hybrids 

 of Drosera, H. Federley, of Helsingfors, who established the fact that in 

 the butterfly hybrid the number of chromosomes is equal to the total of the 

 father's and mother's combined, and O. L. Mohr, of Oslo, who has carried 

 out independent investigations on the reproductive chromosomes and has 

 besides done valuable work in subjects dealt with by the Morgan school. 



Heredity has been the most popular field of research of the age; it has 

 succeeded Darwinism in the way it has taken hold of the public mind and 

 has nowadays to serve as an explanation for anything that presents any diffi- 

 culty in the various spheres of life. Just as formerly it was natural selection, 

 so now it is the mixing of breeds that has to bear the blame for every kind 

 of circumstance and disparity even in human community life, in which po- 

 litical and social prejudices take good care that problems are at least not 

 treated impartially in the scientific sense. As a result of exact heredity- 

 research the theory of evolution has itself been directed along other lines; 

 phylogenetical speculations have for the most part been abandoned — at 

 least for the time being. Natural selection is certainly retained in principle 

 by some students of heredity — by Baur, for instance — but it is really of 

 no practical importance; the phenomenon cannot be observed and it is there- 

 fore not possible to fit it into a subject of research that is based on exact 

 observations. And while the old Darwinism operated with outward resem- 

 blance as a positive proof of common origin, heredity research has established 

 the fact that resemblance and affinity are not analogous terms, thus under- 

 mining the very foundations of phylogeny. Generally speaking, heredity re- 

 search goes to work in a more limited sphere; for the very reason that it 

 has become an exact science it has not been able to follow the old Darwinism 

 in its speculative ranging, but whatever may have been lost in the way of 

 the general conception of life has undoubtedly been won in the way of con- 

 centration on facts and reliable results. 



There are still one or two other subjects for experimental research which 

 must be briefly dealt with in this chapter, and we shall now pass on to 

 these. 



3. Biochemistry 



Application of modern chemistry to biology 

 The science of chemistry as applied to biology has always afforded it valu- 

 able assistance in the search for an explanation of vital phenomena. In mod- 

 ern times, as is well known, chemistry has made splendid progress, and every 

 new step has at once had its influence on our knowledge of living organisms. 

 At the present day biochemistry is a line of research that, in point of the 



