No. 466.] STUDIES ON PLANT CELL. — VIII. 731 



5. The Balance of Nuclear and Cytoplasmic Activi- 

 ties IN the Plant Cell. 



Two regions of the cell are sharply distinguished from one 

 another with respect to both morphology and physiology. They 

 are the nucleus and the cytoplasm. The nucleus soon dies if 

 isolated from cytoplasm and the latter, lacking a nucleus, cannot 

 be kept alive indefinitely unless it be in organic connection with 

 a nucleated mass of protoplasm. The necessary connection 

 may be only through delicate strands, as was established by 

 Townsend ('97), and also seems to be illustrated in the instances 

 of intercellular protoplasm which Michniewicz (: 04) reports are 

 connected by delicate fibrillse (plasmodesmen) with neighboring 

 cells. Some very interesting adjustments of the nucleus and 

 cytoplasm to one another have been reported in a series of 

 investigations of Gerassimow beginning in 1890. His most 

 recent papers of. the past year (Gerassimow, : 04a, : 04b) pre- 

 sent a general summary of his studies and constitute a very im- 

 portant contribution to the subject. They, will furnish much of 

 the material for this discussion. 



Gerassimow has found that the cells of Spirogyra and other 

 members of the Conjugales offer admirable material for the 

 study of the relations between the nucleus and cytoplasm, and 

 throw irnportant light on the functions, physiological activities, 

 and interdependence of both structures. By subjecting fila- 

 ments of Spirogyra during cell division to a temperature of 

 0° C. or treating them for a short time to the anaesthetic influ- 

 ence of ether, chloroform, or chloral hydrate it is possible to 

 arrest the processes of mitosis at different stages with the result 

 that the protoplasm may become variously distributed in the 

 daughter cells, (i) A daughter cell may be formed lacking a 

 nucleus but containing a portion of the divided chromatophore 

 in a peripheral layer of cytoplasm. (2) A single cell may con- 

 tain the two daughter nuclei either separated from one another 

 or more or less intimately associated and perhaps wholly fused 

 depending upon how far the processes of mitosis have pro- 

 gressed before the cells have been subjected to the shock of the 



