



THE CYTOLOGY OF THE SUGARCANE 511 
is pictured in fig. 16. The occurrence of such dyads was strange 
because during the anaphase of 
the heterotype division the chro- 
mosomes are always pretty 
equally distributed over both 
poles. It was shown that this 
strange phenomenon was caused 
by the fact, that at thetimewhen 
the transition wall between’ the 
two dyad-cells had already begun 
to form, the nuclei sometimes 
formed a string-like connection. 
It appeared, that in such cases 
the content of the one nucleus 
passed into the other one. Such 

a nuclear fusion is seen in Berta 
HE ET Abnormalpollen-dyadof EK 28. x 2000. 
In the dyad, figured in fig. 16, the difference in size between the cell 
which contains a nucleus and the 
one which does not, is but small; so- 
metimes the cell without a nucleus 
is very much smaller than the other 
one. Asa consequence of the forma- 
tion of these abnormal dyads, a ve- 
ry abnormalhomotype division took 
place. Sometimes the two nuclear 
plates were, in the metaphase of this 
division, very unequal in circumfer- 
ence, because the one plate contain- 
ed a very large, the other a very 
small number of chromosomes; in 
other cases a very large nuclear plate 
was present in the one cell, while the 
other one did not contain any at all. mary 
Some tetrads showed in two cells a , re oe en EE 
large nucleus, in the other two a 
very small one or none at all. Fig. 18 pictures the latter case alongside 
with a normal tetrad. 

Brems 
