198 KATHARINE FOOT AND E. C. STROBELL. 



responsible for the discrepancy between these investigators and 

 Paulmier, Wilson and Montgomery." 1 



A few facts will serve to convince any unprejudiced cytologist 

 that our method of technique should not be condemned as 

 "inadequate." From many of our preparations it is possible 

 to demonstrate a large number of chromosome groups in which 

 every chromosome is present and can be clearly photographed 

 in one case we have more than 150 photographs of such groups 

 from the same embryo. A method that makes such results pos- 

 sible can hardly be condemned as "inadequate" for "accurate 

 results" it is a method, rather, that compels a recognition of 

 enough variability in the same individual to make one very 

 cautious in accepting premature hypotheses based on insufficient 

 data. 



In further condemnation of our methods McClung criticizes 

 the value of photography as a means of demonstration. He 

 says: "Foot and Strobell have employed photography alone as 

 a means of presenting illustrations of their material, and it is 

 assumed by them that if a thing can be photographed it must 

 necessarily be a true picture of normal conditions. This I 

 consider to be a decided fallacy. A photograph is an inter- 

 pretation by the observer, just as is a drawing. The personal 

 factor is no more absent from one method of illustration than it 

 is from the other. Photographs may present with greater fidelity 

 the details of structure in an object, but the choice of the object, 

 and the nature of details are at the command of the photog- 

 rapher" (pp. 369). 



We certainly do not assume that a photograph must of necessity 

 represent only normal conditions, but we do believe that ab- 

 normalities are likely to be due to a pathological condition of 

 the cells and that such a condition can quite unconsciously be 

 obscured in a drawing, but not in a photograph. McClung's 

 position is certainly unique when he claims that the personal 

 factor is no more absent from a photograph than from a drawing 

 and he bases this on the fact that an investigator may in either 

 case select the object he wishes to photograph. 



1 It is difficult to understand why McClung mentions and underscores "used 

 alone" as on the same page he quotes from our paper in which we distinctly state 

 that we use sections also for "comparative work." 



