﻿VOLUME XXXV 



NUMBER 5 



( 





I 



Botanical Gazette 



MAY, igoj 



ON THE RELATIONSHIP OF THE NUCLEAR MEM- 

 BRANE TO THE PROTOPLAST. 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 



XLVIL 



Anstruther A. Lawson. 



(with plate xv) 



The nucleus has long been regarded as not only the most 

 important, but with its chromatin, linin, nucleolus, karjoljmph, 

 and membrane, it is also regarded as the most complex organ 

 of the cell. Although the literature on plant cytology is rapidly 

 accumulating and revealing much that is of interest on the cen- 

 trosome question, spindle formation, chromosome reduction, 

 etc., we as yet know little or nothing as to the origin and devel- 

 opment of the nucleus. Its morphology is hidden by its com- 

 plexity. This apparent complexity of the nucleus is in a large 

 measure due to the presence of the nuclear membrane. A 

 nucleus without a membrane, as we see it in certain stages of 



I • mitosis, becomes a comparatively simple structure. Such a con- 



dition of the nucleus may be observed immediately preceding 

 spindle formation in the spore mother cells of any of the higher 

 plants. At this stage the nuclear wall disappears, the karyo- 

 lymph becomes diffused throughout the cytoplasm, the nucleo- 

 lus and the linin lose their identity, and the only element left 



\ which can be regarded as nuclear is the mass of chromatin. It 



thus becomes evident that the formation of a membrane is the 

 niost important factor which gives the nucleus its complex 



structure. 



305 



