262 
Rudolf Beer. 
After a careful study of my preparations I have come to the 
conclusion that none of them completely expresses the facts and in 
the present note I will briefly state the results of my study of this 
and of a few other points in the development of these spores. 
The spore-mother cells form a solid mass of tissue in which the 
individual cells are separated from one another by delicate walls 
giving the reactions of pectic bodies. The tapetal cells form a 
continuous layer round the sporogenous tissue. Very soon the 
spore-mother-cells begin to separate from one another by the 
apparent splitting of the delicate walls between them. This 
splitting of the membrane first becomes noticeable at the angles 
between several mother-cells. In the meanwhile the tapetal cells 
have lost their separate individuality and have become fused into a 
plasmodium. This tapetal plasmodium commences to penetrate 
into the interior of the sporangium, making its way between the 
separating spore-mother-cells. It may be noted that tapetal 
cytoplasm, free from nuclei, first advances into the interior of the 
sporangium, and that only after a short, but appreciable interval, 
the nuclei make their way along the cytoplasmic branches between 
the sporogenous cells. At about this stage the division of the 
spore-mother-cells takes place. I have been able to confirm 
Osterhout’s account of the development of the spindle during the 
prophases of the first meiotic division in every particular. The 
chromosomes proved too numerous and crowded to enable me to 
count them with any exactitude. The formation of these bodies 
from the spirem can be followed with comparative ease and is 
particularly interesting in the light of. present day cytological 
discussions regarding this subject. The spirem can be seen from 
an early stage to be double, being composed of two parallel parts 
which usually lie very closely indeed together. This two-fold 
character of the spirem, although often obscured by the intimate 
approximation of the two component parts, was, however, observed 
over and over again when the search was careful and thorough 
enough. 
This double spirem segments into the bivalent chromosomes in 
such a manner that the two constituent chromosomes lie side by 
side parallel with one another. 
Although a certain polarity of the spirem can be seen at one 
period during this division and the thread is then thrown into a 
number of loops, no evidence could be found that the sides of these 
loops become approximated or that they bear any direct relation to 
