The Prophase in the Ovigenesis and the Spermatogenesis of Planaria etc. 443 
A rnass of chromatin lies to one siele of the nucleus. In this muss, 
more or less clear segments can he seen, connected with eacli other 
in a very irregulär way by transverse bands of linin and chromatin. 
Outside the nuclear membrane (wliich is very thin at this stage), and 
closely adjacent to it, is the archoplasm, formed from the remains of 
the spindle. The chromatin bodv (cb.) seen in Figs. 32 and 33 may 
still be seen in some cells at this stage. By this time it takes the 
methvlene blue less strongly than before. Eventually it disappears 
in the cytoplasm (Figs. 36—38). At the same time another chromatic 
bodv makes its appearance (C, Figs. 35 — 45). It is stained brilliantly 
by the satfranin of the triple stain, and becomes marked off from 
the cytoplasm by a clear area (Fig. 36). 
The behaviour of this body is very remarkable. As will be seen 
from Figs. 35—38, there is a very marked resting stage preceding 
the 2nd. meiotic division. Schleii* has overlooked this phase, as, 
although he worked mainly on Planaria gonocephala , yet he says 
that he examined lactea, and Pohjcelis nigra, and found that they 
differed in no way from gonocephala. I have not been able to exa- 
mine gonocephala, as it does not occur in England, but there can be 
no doubt of the existence of this stage in lactea. 
Nor is there any question here of having confused the prophase 
with the telophase of the 2nd. division. The daughter cells of the 
2nd. meiotic division (the spermatids) are only half as large as the 
daughter cells of the first, and their nuclei are markedly smaller. 
Again, figures such as 35 — 38 occur adjacent to cells in the Ist. 
meiotic division, whereas the spermatids seldom do, and even when 
they do, are easily recognisable by the fact that they lie, not com- 
pactly together, but loosely witb spaces betvveen each sperraatid. 
It will be seen then, that the daughter cells of the Ist. meiotic 
division pass through a marked resting stage, characterised by the 
swelling up of the chromosomes to form what looks like a thick 
irregulär spireme (Figs. 36 and 37). 
Shortly before the metaphase of the 2ud. meiotic division the 
chromatin segments become clearer (Fig. 38) rapidly shorten up, and 
then become attacbed to the spindle fibres. 
In the meantime peculiar changes take place in connection with 
the chromatic body in the cytoplasm. 
It lies quite close to the nucleus, and very shortly afterwards a 
large vacuole appears between it and the nucleus. The growth of 
this vacuole must be rapid, for I have not been able to ascevtain its 
