Noteworthy anatomical and physiological researches. 
Some recent cell literature. 
tiquated, perhaps more quickly at present in this field of 
research than in any other. It is now little more than two 
years since the appearance of Hertwig’s admirable summary of 
our cytological knowledge, ‘‘ Die Zelle und die Gewebe,” but 
already certain disputed points there discussed have been fur- 
ther elucidated, and certain views there defended have gained 
or lost in probability. The request of the editors of the GA- 
ZETTE for a brief account of recent literature in its effects on our 
knowledge of the nucleus and centrospheres seems therefore 
justifiable. In this discussion we may best take Hertwig’s 
ook as a starting point; for, although it treats the cell from 
the stand-point of the animal histologist, it shows the thor- 
ough acquaintance of its author with the botanical literature 
and his willingness to use it wherever it can throw light on 
the problems discussed. The present account will, naturally, 
deal chiefly with the literature of the plant-cell, while re- 
ferring also to certain important zoological papers. : 
The question of the nature of the nucleoli and of their 
fate during karyokinesis is still an open one. While Stras- 
burger and others believe that the substance of these bodies 
becomes dissolved in the so-called nuclear sap, it is pretty 
generally held by zoologists to be taken up by the chromo- 
somes. The position taken by Moll (12) may be regarded as 
an extreme form of this view. He finds in the resting nucleus 
of Spirogyra a very large nucleolus which gradually disap- 
pears as the chromatin thread becomes more prominent dur- 
ing the spirem stages. And he believes that he has observed 
the termination of one end of this thread in the nucleolus, 
which thus directly furnishes the material for the formation © 
the chromosomes. Only further studies can definitely decide 
this important question which bears so directly on the nature of 
the nucleoli. Zimmerman (20) has observed, like others be- 
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