C. M. Wen YON 
321 
Nuclear multiplication. The newly encysted gregarines usually 
Lave nuclei with a single large centrally placed karyosome. The 
karyosome soon becomes vacuolated and may break up into several 
fragments. At the same time the nuclear membrane becomes less 
distinct and the karyosome eventually passes into the protoplasm. In 
two cases, in close proximity to the nucleus, another structure has been 
seen which stains more deeply than the surrounding protoplasm. In 
PI. XV, figs. 31 and 32 are shown in sections of a gregarine cyst the 
nucleus with the karyosome in process of breaking up in one section 
and in the next section the elongated staining body which shows some 
sign of radiation at one pole. Figs. 4 and 6 are two adjacent sections 
of another gregarine cyst. In one is seen the nucleus with the 
karyosome in two parts, and in the other a definite spindle forming 
with radiations around the two poles. At each pole is an area of 
denser tissue showino' a few small vacuoles. This denser tissue which 
O 
takes up the stain more deeply than the surrounding protoplasm is 
probably of centrosomic nature. For lack of material it is impossible 
to follow up the stage any further, but there is evidently a preparation 
for the formation of the first nuclear spindle. These stages bear some 
resemblance to the first spindle formation and the “ achromatic mass ” 
described for Metamera schubergi by Duke. 
Though from the material at my disposal I was able to discover 
some trace of the first nuclear division, I was quite unable to find 
a cyst showing the second division. Various stages of the third 
division in a gregarine cyst are shown at PI. XV, figs. 28, 29, 33, 34. 
In one gregarine the division was slightly more advanced than in the 
other. Figs. 33 and 34 are two dividing nuclei of one gregarine. 
There is a centrosome at each pole of the nuclear membrane which is 
still intact. Around each centrosome is a definite astral system. I was 
not able to detect a centriole within the centrosome. Probably had 
I stained with the iron haematoxylin method, further details would 
have been revealed, but all the sections were stained with ordinary 
alum haematoxylin. The chromatin within the nuclei at this stage is 
arranged irregularly. The nuclei in this gregarine were still spherical, 
but in the gregarine associated with it, the spindles were slightly more 
advanced (figs. 28 and 29). The centrosomes have separated and the 
spindle has become elongated. Definite fibres can be seen running 
from one pole to the other and at the centre are several chromatin 
masses. I am unable to say' if at this stage there is a definite number 
of chromosomes. The nuclear membrane, much attenuated, is still 
21—2 
