EXPLANATION OF PLATES. 
The drawings in plates 1 to 9 were in all cases made with the aid of a camera 
lucida, using a Zeiss No. 12 compens. ocular and a Spencer homogeneous 
immersion 1.8 mm. objective, N. A. 1.30. Drawings no. 63-65 were made at a 
magnification of 2,600 diameters, all the others at a magnification of 3,000 
diameters. The drawings have been reduced one third in reproduction. 
Plate 10 consists of photomicrographs made at a magnification of 1,150 
diameters. 
SYMBOLS USED: 
A designates selected chromosome-pair “A.” 
B “ “ “ «a OS 9 Bp oe 
(C “ “ “ “ LIS (Cle 
x accessory chromosome. 
G composite granule. 
g & polar granule. 
