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J. BRONTE GATENBY. 
the chromosomes hardly at all ; this might be a useful 
reaction in some work (see PI. 25, fig. 48). 
The Probable Nature of the Micromitosome. 
Some observers have referred to this body as a “chromatin 
granule.” If one stains in pyronin and methyl green the 
micromitosome is red, and the chromatin green. 1 Iron 
Haematoxylin is not a specific stain for chromatin, and the 
fact that it stains the micromitosome darkly, merely means 
that the latter is of a dense nature. If the micromitosome 
really divides autonomously it resembles the centrosome 
somewhat in this way, but the Regaud test shows that the 
centrosome will not stain where the micromitosome will. 
According to the Regaud reaction the latter resembles 
mitochondria more than chromatin, but the value of the 
test is doubtful. The important fact to be noticed is that 
very probably the micromitosome is altogether of a different 
nature from chromatin, and should not be loosely called a 
“chromatin granule.” Montgomery (9) calls certain bodies 
he finds “ chromatoid granules,” which is non-committal. 
Discussion. 
The few facts brought together in this paper show that 
Meves’s schematic comparison of the bodies in the sperma- 
togonium and the spermatid probably does not hold good for 
the Lepidoptera. In particular I have the greatest suspicion 
of the view at present current, that the acrosome is derived 
from the arclioplasmic idiosome detached from the centro- 
somes. I believe that at present such a view cannot be 
entertained for a moment in Smerinthus or any other Lepi- 
dopteran upon which I have worked, and when the sperma- 
togenesis of the mammal has been more carefully studied, I 
think that the acrosome will be found in the growth stage, as 
a body independent of the centrosome, at every stage of its 
existence. 2 
1 This, however, does not show that the micromitosome is not 
chromatin ; for in later stages (spermiogenesis) the nucleus also 
becomes red for a time. 
2 In Helix aspersa the acrosome has no relation to the archoplasm. 
