DESCRIPTION OF PLATES 



With the exception of Figs. 59, 65, 73 and 82 for which a Zeiss 1.5 mm. obj. was used, the figures 

 were all drawn with a Zeiss 2 mm. oil immersion obj. and a 2^iss compensating oc. 12. The magnifica- 

 tion was doubled with a drawing camera, and the figures were then reduced one-half, giving a magni- 

 fication of 1500 diameters. 



Lettering on plates 



h = a. heterochromosome or a pair of heterochromosomes. 



h\ = the larger heterochromosome. -w 



h2 = the smaller heterochromosome, 



m = an w-chromosome (Wilson). 



p = plasmosome. 



X = middle part of In in Drosophila. 



