Nuclear Division in the Hepaticae. 477 
form of spindle-shaped rods. The nucleolus in the mean- 
while fragments, and the particles become attached to the 
rudiments of the young chromosomes, often in a very striking 
manner 1 * ; there exists a good deal of variety, however, in the 
extent to which this relation of nucleolus and chromosome- 
rudiment obtains. One thing is however clear, that as the 
chromatin increases in the latter, the nucleoli become less 
and less easily differentiated, although traces of them can 
sometimes be observed even up to the time of the differentia- 
tion of the achromatic spindle. This body appears with great 
suddenness, and this particular material is not very suitable 
for tracing out its genesis, but from the relation of the drawn- 
out nucleus with the centrospheres it seems highly probable 
that it is for the most part of nuclear origin. There is, 
besides the so-called ‘ nuclear sap,’ the unused linin which 
does not enter into the constitution of the chromosomes, and 
also possibly a part at any rate of the nucleolus which might 
serve as material out of which it could be differentiated within 
the nucleus. My own observations have rendered me sceptical 
as to the existence of a special spindle-forming substance, and 
I regard it as not improbable that the spindle represents 
nothing more than hyaline protoplasm (using the term in its 
widest sense) which has become strained along 5 lines of force.’ 
Thus, for me, it is not a very important matter whether the 
spindle is of cytoplasmic or of nuclear origin, especially as we 
know that it may be either of entirely nuclear or of mixed 
origin, taken that is as a whole. To this question I shall 
return later. 
The chromosomes, eight in number, lie along the spindle 
in the equatorial plane, and they very clearly exhibit a hump 
in the middle of each one of them, similar to the hump seen 
in the chromosomes of Lilies during the first mitosis in the 
pollen-mother-cell. It is not very easy to follow out the true 
course of events in Fossombronia , owing to the minuteness of 
the chromosomes, but I think I am justified in saying that the 
1 Cf. Strasburger, Die Controversen d. indirecten Kerntheilung, p. 23. 
L 1 
