ging chromosomes found varied from eight to seventeen. 
Laggards at anaphase I were found in every sporocyte. 
As soon as the division process reached the quartet stage, 
several micronuclei were always produced around each 
quartet. 
In every preparation, the microsporocytes in this form 
of Tripsacum flavum appeared much larger than those in 
the form of 7. australe discussed below. 
Tripsacum australe Cutler and Anderson 
The pachytene chromosomes in the plants of this spe- 
cies were much easier to study. The number of bivalent 
chromosomes ts definitely 18; in other words, it is a dip- 
loid with 86 somatic chromosomes, At late pachytene, 
spindle fiber attachment regions offered even better work- 
ing material than those of maize chromosomes. Length 
and arm ratio of each chromosome could be averaged out 
as soon as several measurements had been made. Chro- 
mosome 8 has a small internal knob on the long arm 
(Plate NX, fig. 3). As illustrated in Plate N NI, chro- 
mosomes 1, 4, 11 and 15 have a knob terminating the 
long arm. The spindle fiber attachment regions of chro- 
mosomes 2, 10 and 16 appeared median. Knobs are not 
present on the short arms of any of the eighteen chro- 
mosomes. 
As shown in Plate N NI, it is possible to divide the 
chromosomes into two groups, A and B:; group A has 
the nine long chromosomes, and group B the nine short 
ones. The length of the shortest chromosome among the 
nine long chromosomes in group A is about equivalent 
to the length of maize chromosome 10. The length of 
the longest chromosome among the nine long chromo- 
somes of the same group is about equivalent to the 
length of maize chromosome 4. Nevertheless, the arm 
ratios of most of the nine long chromosomes are differ- 
[101 J 
