A CRITICAL EXAMINATION 41 



We have in the past not lacked chemical theories 

 of heredity. One has but to mention the names 

 of Pfliiger, Verworn, Hatschek, Kossel, Adami, 

 Guyer, and many others to recall such theories to 

 mind. The difficulty, it would seem, under which 

 all such theories have labored is that, in the ab- 

 sence of the developed biochemical technique now 

 available, these theories have not been framed on a 

 practical basis; that is, they have lacked the 

 very essential property of being capable of direct 

 experimental test. The time seems now ripe for 

 a biochemical theory of the hereditary process, 

 which in the light of our present knowledge and 

 technical equipment in the fields of statistical 

 mathematics, experimental breeding, cytology, 

 and biochemistry, shall be adapted to experi- 

 mental verification or disproof as the case may be. 



Finally, if, as I fear may be the case, I have 

 wearied the reader unduly with this discussion of 

 methods, instead of conducting him on a journey 

 into the more exciting field of results, my apologia 

 must be that, however irksome and disagreeable 

 the task, an occasional examination and overhaul- 

 ing of one's equipment is as essential to success 

 in scientific operations as it is in military. The 

 geneticist's working equipment is a good one, and 

 has wrought well. I hope it has done no harm 

 to try to see just what the limitations are to the 

 usefulness of each tool in the list. 



