210 
H. M. WOODCOCK. 
We are now in aposition to summarise, compai-atively, the 
various types of nuclear condition which have been described 
in different Hgemogregarines. InKaryolysus lacertaa a 
defiuite karyosome is present in the youngest schizonts. This 
undergoes premitotic division which is usually unequal. The 
smaller half divides again, and the resulting portions ulti- 
mately become incorporated with the general nuclear matei ial ; 
the larger half of the karyosome, on the other hand, is 
eliminated from the nucleus and passes to the suiface of the 
body-protoplasm, becoming altered and probably partially used 
up by the cytoplasm in its passage.^ As already mentioned, 
I am of the opinion that the division-centre persists in the 
modified nucleus and can be seen at times as a definite centi-al 
gi’anule. I am unable to say whether a karyosome is deve- 
loped again in a later phase of the life-cycle. In Hepato- 
zoon (Hasmogregarina) canis, according to Wenyon (37), 
the karyosome pei-sists throughout the schizogony, its division 
occurring in the usual prornitotic manner; in this case, the 
body regarded by Wenyon as a karyosome is very small com- 
paratively, andj I should say, represents little more than the 
intra-nuclear division-centre itself. Wenyon does not mention 
whether he observed any elimination of chromatic material 
before or during schizogony. On the other hand, in HEemo- 
gregarina nicoriae a karyosome cannot be distinguished at 
all, the nucleus appearing in all phases to have its chromatin 
more or less regularly distributed upon a reticular framework 
a definite intra-nuclear centrosorne is regarded, however, as 
being present. H. stepanovi shows, as T consider, a very 
interesting stage in the disappearance of the karyosome as a 
distinct organella. In certain phases a nucleolus is present, 
' It is instructive to note that a similar elimination of karyosomatic 
material before the yoimg schizontf proceeds to nuclear multiplication 
is described by Averintzeff (1) in the case of Barrouxia sp., parasitic 
in Cerebratulus. The process may apparently take place according 
to one of two slightly different modes, the second of which funiishes a 
close parallel to the nuclear behaviour of the corresponding phase in 
Kary oly sus. 
