404 FOUNDATIONS OF BIOLOGY 



between successive generations. Indeed, the present science 

 of genetics has a history largely confined to this century. 



Although clearly intimated by a number of workers, the 

 conception of the continuity of the germ cells was first forced 

 upon the attention of biologists and given greater precision 

 by WEISMANN (1834-1914) of Germany in a series of essays 

 culminating in 1892 in his volume entitled The Germ Plasm. 

 He identified the chromatin material which constitutes the 

 chromosomes of the cell nucleus as the specific bearer of 

 hereditary characters, and emphasized a sharp distinction 

 between germ cells and somatic cells. 



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 characters of animals and plants as 

 exhibited in parents and offspring. The studies of this type 

 which first attracted the attention of biologists were made by 

 GALTON (1822-1911) of England. In the eighties and nine- 

 ties of the last century, he amassed a great volume of data 

 in regard to, for example, the stature of children with refer- 

 ence to that of their parents, and formulated his well-known 

 'laws' of inheritance. But the work which eventually 

 created the science of genetics was that of GREGOR MENDEL 

 (1822-1884) of Austria. Mendel combined in a masterly 

 manner the experimental breeding of pedigree strains of 

 plants and the statistical treatment of the data thus secured 

 in regard to the inheritance of sharply contrasting characters, 

 such as the form and color of the seeds in Peas. Mendel's 

 work was published in 1863 in an obscure natural history 

 periodical, and he abandoned teaching and research to be- 

 come the Abbot of his monastery. Thus terminated pre- 

 maturely the productive work of one of the epochmakers of 



