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II. M. WOODCOCK. 
plastiu or allied material. Reiclieuow, however, regards this 
element as a nucleolus principally on the ground of its 
behaviour during nuclear division, that is to say, its 
disappearance and re-formation at different periods. Unfor- 
tunately, Reichenow’s observations on this body in II. 
stepanovi, whicli have led him to the conclusion that it has 
the physiological significance of an ordinary nucleolus, have 
prejudiced his view upon the true karyosome, which is some- 
thing quite different. lie has, in my opinion, failed to grasp 
what is the really essential feature of a true karyosome, 
namely, that it is a chromatin-nucleolus, an organella 
which holds or contains a large proportion of the entire 
chromatic substance of the nucleus. His only reference to 
this fundamentally important character is seen in the 
following sentence: — ''Was ihn [d. h. den Biunenkbrper 
(Karyosom)] von dem echten Nucleolus untersclieidet ist, 
abgesehen von seineni Chromatingehalt auf den wir keinen 
grossen Wert legen diiifen, allein der Uinstand, dass er 
bei der Kerntheilung erhalteu bleibt ” (the spaciug is mine). 
Because he thus ascribes no importance to this, the principal 
feature of the karyosome, he is able to persuade himself that 
the typical " Binnenkbrper ” or karyosome in other cases is 
the equivalent, practically speaking, of the body he has 
described in U. stepanovi. 
Further, Reichenow brushes aside as quite untenable the 
usually accepted view that the karyosome behaves as an 
intra-nuclear division-centre, which is founded on the reliable 
observations of many previous workers. The admitted exist- 
ence of the " Hantel-Figur ” he endeavours to explain by 
supposing that it is produced by the karyosome being drawn 
out into two parts by the separating halves of the dividing 
nucleus. He appears to have adopted this attitude on two 
grounds : in the first place, because he has found that the 
nucleolus of H. stepanovi does not so divide, and secondly, 
because he evidently doubts the existence at all of an intra- 
karyosomatic centrosome and the occurrence of promitotic 
division, so far as the Coccidia and Ilsemosporidia are con- 
