7 1 6 Beer —Studies in Spore Development . II. 
karyolymph, if secreted by the chromosomes, is in this case excreted 
immediately without ever collecting in visible vacuoles within the chromo- 
some bodies. The fact that these chromosomes enlarge somewhat as they 
move apart is probably due to the formation of karyolymph diffused within 
their substance, but which does not collect in definite, visible vacuoles. 
Homotype Division. 
Some difference in the behaviour of the nuclei during this division 
is shown between Matricaria on the one hand, and Tragopogon and Crepis 
on the other. The prophases of this division, to a great extent, re- 
traverse the ground gone over in the telophase of the heterotype division, 
and since Matricaria maintained the individuality of its chromosomes 
almost intact throughout the period of interkinesis, fewer steps are required 
in their reconstruction and their arrangement upon the equator of the 
spindle. The fine, connecting branches joining together the chromosomes 
during interkinesis are withdrawn, and the substance of the chromosomes 
becomes concentrated into short, rounded bodies. These take up their 
position upon the equator of the spindle, and it can then be seen that each 
chromosome is divided into two halves (Fig. 38). The two halves of each 
chromosome are separated from one another during the anaphase of the 
division and travel to the poles. During this passage to the poles they 
remain short, stumpy bodies. Reaching the poles the daughter chromo- 
somes become closely arranged together, as was the case at the conclusion 
of the heterotype division. A little later a colourless nuclear sap collects 
between and round the chromosomes, and separates these from one another, 
but, as in the preceding division, the chromosomes remain adherent at certain 
spots (Fig. 39). A nuclear wall is deposited, and the chromosomes move 
more widely apart. Fig. 40#, PI. LXV 1 I, represents this stage. In the 
later history of these nuclei no vacuolization of the chromosomes is to be 
seen, but their substance appears to become gradually distributed along the 
anastomosing branches which connect them together. A successive series 
of stages is represented in Fig. 40, a-d. 
There is some variation, however, in the degree to which the substance 
of the chromosomes becomes distributed in these nuclei. Sometimes, as in 
Fig. 40 d, the distribution is fairly complete, whilst in other cases the 
chromatin remains 1 aggregated in masses of varying number and size. 
F'ig. 41 a, PL LXVI, is drawn from a young pollen-grain at the same stage 
of development as Fig. 40 d, whilst Fig. 41 b is from quite a late stage in 
pollen development (but some time previous to the division of the nucleus 
of the pollen-grain). 
These differences in the state of aggregation of the chromatin no doubt 
1 Or it may possibly have again become aggregated into such masses after first having been 
distributed. 
