A CRITICAL EXAMINATION 35 



cal, observational method. It is essentially a 

 static method. It labors constantly under the 

 very serious danger of error which inheres in 

 inferring the course and nature of dynamic 

 events by observation only of their static ante- 

 cedents or consequences. In the second place, 

 the technical difficulties of the material make it, 

 in most instances, practically impossible to apply 

 the experimental method directly to the cytological 

 side of the problem of heredity. In spite of these 

 limitations, cytology has made and will continue to 

 make fundamental contributions to the progress of 

 research in heredity. It is one of the essential 

 methods of investigation in this field. 



4. The Embryological. 



Embryology has chiefly been cultivated for its 

 own ends, which are, on the one hand, those of 

 descriptive morphology and, on the other hand, 

 those of a special field of physiology, Entwick- 

 lungsmechanik. Only in a relatively small pro- 

 portion of instances has it been directly and pur- 

 posefully used as a mode of research in genetics. 

 Yet embryology is the science of somatogenesis, 

 which was shown at the beginning to be one of 

 the fundamental elements of the problem of 

 heredity. It is a little difficult to understand 

 why, with such splendid opportunities as the em- 

 bryological method offers, so little light regarding 

 the hereditary process seems to have come from 

 the embryologist. To say this is not in the least 



