Acetocarmine squash preparations were made of young 
anthers. Appropriate nuclei were photographed, and 
camera lucida drawings were made of them from tempo- 
rary preparations. Chromosomes were measured from 
camera lucida drawings alone, and their lengths, which 
include the centromeric regions, are expressed in micron 
units. Numbers are assigned to chromosomes on the 
basis of decreasing order of length: thus chromosome 1 
is the longest of the complement. Individual chromo- 
somes are identified on the basis of their length, arm- 
ratio (length of long arm/length of short arm), and the 
pattern of distribution of heteropyenotic and eupycnotic 
region. 
Observations 
Coixv aquatica Roxb. The chromosomes of this species 
are difficult to study at pachytene, because they are long 
and often intertwined. In addition, the chromosomes 
possess long heteropyenotic segments which often ex- 
hibit non-homologous association (Plate LV), thereby 
making it difficult to follow the chromosome from one 
end to the other. Deep staining heteropycnotic regions 
are present in the proximal regions of both arms. Addi- 
tional heteropyenotic regions are present at other loca- 
tions on the chromosome arms. ‘The chromosome arms 
terminate in pronounced and dark staining chromomeres. 
Exact measurements of the heteropycnotic regions were 
not possible to obtain, because of variability in their ex- 
tent (see Venkateswarlu and Chaganti, 1973). Camera 
lucida drawings of the five chromosomes are represented 
in Plate LVI, while the idiogram represented in Plate 
ILX is based on mean values of length and arm ratio of 
five measurements for each chromosome (see Table II). 
The third longest chromosome of the complement has 
the nucleolus organizer in the long arm in a sub-terminal 
position (Plate LX). 
