576 
Humphrey. — On some 
improbability of a genetic connexion between the two sorts 
of bodies. It should quite satisfy any sceptic to examine 
such preparations as those from which Figs, i, 9, and 10 are 
drawn with all possible exactness. 
The behaviour of the centrospheres with reagents warrants 
a distinction between the denser slightly stainable centro- 
some, and the enveloping, highly refractive, and as yet 
unstained astrosphere. The substance of both appears to be, 
in general, protoplasmic ; but the idea of its special character 
has been expressed in the terms cu'choplasm and kinoplasm , 
applied to it by Boveri and Strasburger, respectively. What 
we know of it seems to me to point to its specific nature. 
Whether the centrospheres are permanent organs of the cell it 
is impossible to say with certainty. So far as the astrosphere 
is concerned, Boveri (’95) denies this for animal cells, which 
afford much more satisfactory material than plants. It may 
well be that their substance contributes more or less to the 
formation of the spindle or is otherwise distributed in the cell. 
Such a fate would readily explain the difficulty of observing 
them in some stages of karyokinesis in Pellia. And the 
centrosomes, as has been said, would be quite unrecognizable 
without the characteristic envelope of the astrosphere. Yet in 
Pellia the centrospheres are most clearly seen when the 
radiations about them are most distinctly developed. This 
hardly supports the idea of the formation of the radiations 
from the substance of the astrosphere. On the other hand, 
the astrosphere appears, in the case of Psilotum, to be constant 
in all stages ; and my observations on Osmunda point to the 
same conclusion. It appears, then, that the centrospheres 
show no essential changes in their appearance, except when 
they are themselves undergoing division. If we omit the 
observations of Lauterborn (’93) on some Diatoms, and of 
Wager (’94) on a species of Agaricus , both of which seem 
to require confirmation, the structure and behaviour of the 
centrospheres in plants is strikingly uniform, so far as known. 
Judging from present knowledge, one may be warranted in 
believing it probable that these structures will prove to be 
