FORMATION OF THE FIRST SPERMATOCYTE CHROMOSOMES 571 



;;••• v.* ••;: ••;• 



A B ' C D 



.•.V .;-. At ••;•••. 



••!;2 •.:*• •••• •*• 



E P G H 



• ••• •• % %\t \ tf 



•••• •^ • ••• ••• 



•V- , •% ,• 



/ * J K L 



\\\% **Mt t\%% \\Xl 



M NOP 



Fig. 5 Specimen 34-1. A, B, C, D, second spermatocyte divisions, pole views, 

 showing 12 chromosomes; E, F, G, H, the same with 13 chromosomes; /, J, meta- 

 phase plates, first spermatocyte division, 12 chromosomes; K, L, second division 

 anaphase, polar views, of both chromosome groups from the same spindle; M, N, 0, 

 serial sections, side views, of a metaphase plate of the first division showing that 

 all chromosomes are bivalent; P, early anaphase of the second division showing 

 one elongated chromosome. 



gave 12 chromosomes. These specimens show clearly that by 

 working on a limited amount of material, an observer might be 

 led to believe that no irregularities were present. It is only 

 by a comparative study of a large number of individuals that we 

 may hope to reach a true solution of these difficulties. 



