178 CHARLES L. PARMENTER 



sketching it. The chromosomes were then numbered consecu- 

 tively, the number being placed on both ends of each chromo- 

 some. This method avoided any possibility of overlooking any 

 chromosome or of counting any chromosome twice. 



2. Clearness and classification of the complexes. All the com- 

 plexes counted were polar views of late prophases and of meta- 

 phases and have been divided into three classes on the basis of 

 their clearness. The first class consists of forty-five complexes 

 in which every chromosome was so clearly separated from adja- 

 cent chromosomes that it could be optically traced continuously 

 over its entire length, without losing sight of it at any point. 

 Only the counts from complexes of this group are submitted 

 as data which are unquestionably free from objection and 

 uncertainty. 



In the second class of cells there are eighteen complexes in 

 which the chromosomes are all exactly as clear as those of the 

 first class, with the exception that either one or two chromosomes 

 cannot be clearly traced over their entire length as they could 

 be in class I and therefore might possibly be hypercritically 

 considered to necessitate interpretation. 



The three cells of the third class differ from those of the 

 second class in that they each contain places in which the number 

 of chromosomes cannot be determined with confidence and 

 consequently are actually subjects for interpretation. 



Complexes of the first class. Complexes of this class are 

 represented by figures 1 to 8 which have been made in carbon 

 and are attempts to represent the actual appearance of the 

 chromosomes and their relative positions in the complexes. Rep- 

 resentative cells from each of the tissues studied, except the 

 mesentery and lung, have been so drawn. Other complexes of 

 this group have been outlined in ink, figures 9 to 20, to give a 

 further assurance of the nature of the complexes constituting 

 this class of conditions. 



Since it is impossible to represent chromosomes in a drawing 

 as clearly as they are seen in a cell, it is necessary to consider 

 briefly this situation in order to prevent misunderstanding, and 

 incorrect impressions concerning the clearness of the cells and 



