DEVELOPMENT OF BIOLOGY 



469 



(1834-1914) of Germany in a series of essays culminating in 1892 

 in his volume entitled The Germ, Plasm. He identified the chro- 

 matin material which constitutes the chromosomes of the cell 

 nucleus as the specific bearer of hereditary characters, and em- 

 phasized a sharp distinction between germ cells and somatic cells. 

 (Figs. 181, 305.) 



While this viewpoint had been gradually gaining content and 

 precision, the science of genetics had been advancing not only by 

 exact studies on the structure and physiology of the germ cells, but 

 also by statistical studies of the results of heredity — the various 



Fig. 305. 



August Weismann. 



characters of animals and plants as exhibited in parents and off- 

 spring. The studies of this type which first attracted the attention 

 of biologists were made by Galton (1822-1911) of England. In 

 the eighties and nineties of the last century, he amassed a great 

 volume of data in regard to, for example, the stature of children 

 with reference to that of their parents, and derived his well-known 

 ' laws ' of inheritance. 



But the work which eventually created the modern science of 

 genetics was that of Mendel (1822-1884) of Briinn, Austria. Men- 

 del combined in a masterly manner the experimental breeding of 

 pedigree strains of plants and the statistical treatment of the data 



