﻿1 903 1 CURRENT LITER A TURE 225 





nucleate cells can grow somewhat in length. The non-nucleate chamber 

 (which is distinguished from the non-nucleate cell by a larger or smaller 

 opening in the partition separating it from its sister cell with the superabund- 

 ance of nuclear material) grows more vigorously than the non-nucleate cell. 

 Cells with a superabundance of nuclear material can conjugate with each 

 other or with ordinary cells, and the size of the zygospore is in direct relation 



to the size of the conjugating cells. — Charles J. Chamberlain. 



The conxlusion of a paper by Mairuchot and Molliard on the changes 



produced by freezing in the structure of plant cells, enables us to present a 

 summary of their conclusions. '3 



The freezing of tissues always creates a demand for water at the exterior 

 of the cell which produces a general and rapid outgo both of the water of 

 I the cell sap and the water of imbibition held by the protoplasm, resulting in a 



vacuolization of the latter, by which the cytoplasm becomes alveolar, and the 

 nucleus a network of thick filaments and large meshes. The water once 

 extracted from the plasma makes its way into the sap cavity either by 

 simple osmosis, as is generally the case for the nucleus and probably for the 

 cytoplasm, or by the bursting of the vacuoles and the escape of their contents 

 outward, as in certain nuclei, 



Exosmose of the water from the cytoplasm does not produce any easily 

 observed structural modification. In the nucleus, however, the currents pro- 

 duced by the rapid exit of water in response to the demand from without, 

 determino a uni-, bi-, or multipolar orientation of the nucleoplasmic frame- 

 work, according as there are one or more directions of easy exit from the 

 water. The "poles" are more watery and consequently less chromatic than 

 the rest of the nucleus. They are always related m position to the sap 

 cavity; the thinner the layer of protoplasm which separates the nucleus from 

 thesap cavity the easier the'exit and the more distinct the "pole." When 

 very thm the wall of the nucleus may even be ruptured, letting the water 

 escape bodily into the sap cavity. 



The same alterations of structure as are produced in cytoplasm and 



nucleus by freezing can be produced by depriving them of water by other 



"leans, ^.^., by plasmolysis and by natural or artificial drying. The cyto- 



ogical evidence thus confirms Molisch's theory that death by freezing is in 



reality death by desiccation. 



It will be evident at once that this paper has an important bearing upon 

 certam cytological problems, since our modes of killing and fixing involve 

 t e relatively violent withdrawal of water, which the authors declare deter- 

 nimes the orientation of nuclear material.— C. R. B. 



Shibata^4 \^ an interesting preliminary paper records his experiments 



^^^ '^Matruchot, L. and Molliard, M., Modifications produites par le gel dans la 

 ructure des cellules vdgetales. Revue Gen. Bot. 14: 401, 463, 522. 1902. 



Shibata, K., Experimentelle Studien liber die Entwickelung des Endosperms 



onotropa. (Vorlaufige Mitteilung.) Biol. Centralbl. 22: 70S- 7M- ^902 



