186 The Cytology of two Species of Characiopsis. 
Characium angustum differs widely from these two species of 
Characiopsis with regard to nuclei, but on the other hand Characium 
Sieboldii is almost exactly similar, the young individuals containing 
only one nucleus, which divides hy successive bipartitions as in 
Characiopsis saccata until in adult specimens there are thirty-two 
to sixty-four. 
Thus as far as the nucleus is concerned there are no essential 
differences between Characiopsis and Characium, since the uni¬ 
nucleate condition of the cell is not constant in the latter genus. 
In the chromatophores there are apparently great differences 
between the species of Characiopsis and Characium under con¬ 
sideration, since in Ch. angustum and Ch. Sieboldii there are no 
definite chromatophores, whilst in both Characiopsis Ncegleii and 
Ch. saccata the chromatophores, whilst not being in the least 
similar to each other, are nevertheless well-defined from the 
colourless cytoplasm. On the other hand, however, it has still to be 
proved that chromatophores are universally present in Characiopsis 
and altogether absent in other species of Characium, so that this 
difference of chromatophores is only a possible distinction between 
the two genera. 
Thus after the consideration of these four species the only 
constant differences which can be distinguished between the two 
genera remain, as before, in the presence of pyrenoids and the 
occurrence of starch in Characium and their entire absence from 
Characiopsis, the latter genus storing its food reserve in the form 
of oil. 
In conclusion, I wish to express my thanks to Professor 
G. S. West for much help and advice during the course of the 
investigation. 
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