PAS C. CLIFFORD DOBELL. 
one end of the spindle at the beginning of division (fig: 72), 
the “ spindle ” itself being really club-shaped. As the spindles 
draw out thekaryosome granules travel along the spindle-fibres 
(fig. 73, lower spindle), and finally some of them reach the 
opposite end and give rise to the distal daughter-karyosome 
(fig. 738, upper spindle). Constriction of the spindle then 
takes place, as in the case of the first spindle, and finally four 
nuclei are formed in the cyst (figs. 74, 75). As will be 
apparent from the figures, the two secondary nuclei do not 
always divide simultaneously. 
The next thing which happens.is the removal of the chro- 
matin masses in the cytoplasm. In many cases this is appa- 
rently absorbed, for it stains paler and paler, and gets smaller 
and smaller, and all fully-developed cysts are quite without 
free chromatin (fig. 77). But I have found a number of cysts 
which appear to indicate quite clearly that the chromatin is 
sometimes removed directly by extrusion from the cyst 
through the membrane (cf. fig. 76). Apparently, therefore, 
it may be got rid of in either way. 
In addition to losing its chromatin masses the cyst now 
loses its vacuole (figs. 76, 77, 79). After this the cyst becomes 
slightly thicker and more yellow in colour, It contains the 
four nuclei (the product of the two nuclear divisions), each of 
which has a very characteristic appearance—that of a ring 
with a central karyosome granule (fig. 77). The structure of 
the nuclei can be seen quite clearly in the living cyst (fig. 79). 
Each nucleus measures about 3 wu in diameter—that is, half 
the diameter of the original single nucleus which was present 
in the cyst (fig. 64). 
animal the spindles are seen to grow across from one side of the cyst 
to the other. Then, again, we should expect to find the projections 
turned towards one another if they were the results of the first division. 
But actually they are often directed in opposite directions (ef. fig. 71). 
It should also be noted that the spindles of the second division remain 
pointed at only one end until quite late in development (cf. both 
spindles in fig, 73), All the facts are in favour of the interpretation 
given above. 
