368 KANSAS UNIVERSITY SCIENCE BULLETIN. 



is spread upon glass slips and allowed to dry. (Foot and 

 Strobell, '07, p. 282.) In this condition it is stained with 

 Bismark brown and mounted in balsam. Entire reliance is 

 placed in this method, and little attempt is made to correlate 

 the results thus obtained with the appearances presented by 

 other systems of technic. That the position of these authors 

 on this point may be clearly understood, I quote their state- 

 ment of the case. 



"Professor Wilson, in his recent paper in Science, February, 

 '07, replying to our preliminary note, says that he thinks the 

 contradiction in our results is probably due to the difference 

 of method employed, we having placed our faith in smear 

 preparations, while he has relied on sections. We are glad 

 of an opportunity to emphasize this faith, believing that for 

 demonstration of the structure and count of chromosomes our 

 modified smear preparations are more reliable than sections ; 

 and it is for this reason we have abandoned the use of sections 

 in studying chromosomes, except for comparative work and 

 for studying the topographical relation of the cells. In cells 

 fixed and sectioned nearly all the delicate details shown in 

 the chromosomes of our smear preparations are completely 

 lost, and it ought to be too obvious to mention that a method 

 which presents clearly each individual chromosome in its in- 

 tegrity offers decided advantages when the question of accu- 

 rate counting assumes the importance and develops the con- 

 tradictions familiar in recent literature." 



The authors state that they have used sections for com- 

 parison and topographic work, but none of their photographs 

 are made from sections, and their entire argument, as pub- 

 lished, is based upon material prepared according to their 

 own method. 



It is my judgment that this method, used alone, is entirely 

 inadequate for accurate results, and in this particular case is 

 responsible for the discrepancy between these investigators 

 and Paulmier, Wilson and Montgomery. From the work of 

 Miss Pinney it will be clear, I think, that in the prophases 

 figured by Foot and Strobell there are two darkly staining 

 bodies, the accessory chromosome and the plasmasome, instead 

 of the one shown in their photomicrographs. Owing to the 

 technic employed by them the plasmasome is practically de- 

 stroyed, and instead of using other methods to determine the 



