Humaria rutilans, Fries. 39 
later the centrosomes reach opposite ends of the nucleus, and the monaster 
is formed. 
Up to this time the membrane has been perfectly distinct and the 
space enclosed by it almost free from granules, but, from now onwards, 
the nuclear area becomes much less evident, though it can still be traced 
for some time. 
The aster is demonstrated only with difficulty, but in favourable cases 
faint radiations may be seen passing away from the centrosome to be lost 
in the cytoplasmic reticulum. 
The mature chromosomes, though so much contracted that the fact 
is more or less disguised, are typically V-shaped bodies, both limbs of 
which have undergone longitudinal fission throughout their length. Each 
chromosome lies on the spindle in such a way that one of its limbs is 
directed to either pole ; the two limbs then separate, the bivalent chromo- 
some being thus transversely divided. In the meantime, the longitudinal 
split becomes evident (Fig. 30), and each half of the bivalent chromosome 
thus passes to the pole as a V-shaped structure (Fig. 31). Sometimes 
one limb of the daughter chromosome remains attached to its fellow on 
the opposite half of the spindle after the other has broken away ; the 
attached limb becomes considerably drawn out, and irregular figures are 
thus formed (Fig. 30 a). 
The chromosomes become closely aggregated at the poles (Fig. 33), 
and reconstruction of the daughter nuclei begins. During this process the 
outline of the chromosomes can for some time be distinguished (Figs. 33, 34). 
In the prophase of the second division, sixteen stout V-shaped chromo- 
somes, no doubt representing those of the first telophase, reappear. They 
become attached to the spindle either at the apex of the V, or, more 
usually, about half way along its limbs (Fig. 35). The limbs separate and 
pass to opposite poles, being straight or bent according to the position 
in which they are attached to the spindle ; the bent chromosomes are of 
much the more common occurrence (Fig. 36). 
The. longitudinal fission begun in the prophase of the first division, 
before the formation of the definitive nucleus, is thus completed. 
Spindle formation takes place as in the first division, and the centro- 
somes, here also, are large and discoid. 
The four nuclei of the ascus now pass into a stage of rest which, as 
it was frequently encountered, probably lasts for some time. 
The Third Mitosis. 
At the beginning of the third division the chromatin of each nucleus, 
forms a delicate spireme (Fig. 37), which breaks up into sixteen curved 
chromosomes (Figs. 40, 41). Rounded bodies are present either near 
together (Fig. 38), or at opposite ends of the nucleus (Fig. 39) ; they 
