1 64 G. L. Kite 



Many of the physical and chemical changes of cell-division are 

 reversible. Pressure on the cell plate of spermatocytes in telophase 

 has caused rapid fusion of the daughter cells and extensive swelling 

 and loss in rigidity of the protoplasmic gel in which the spindle fibres 

 are imbedded. If the displaced spindle fibres and chromosomes are 

 dissected out, after such a partial reversal, they are found to have 

 undergone no appreciable change in rigidity. 



From a preliminary study of mitosis, a few conclusions, that are 

 probably general, can be drawn. It seems that cell-division results 

 primarily from concomitant shrinking and swelling or change in water- 

 holding-power of different portions of the cell protoplasm. Many of 

 the structural elements of the mitotic figure separate out of the pro- 

 toplasm and change in rigidity according to their water-content. 

 During the prophase, the nuclear substance becomes so soft that 

 movement of the components of the nucleus is affected by flowing 

 of the nuclear gel. The mechanism at the basis of this flowing seems 

 to be a change in water-holding-power of the nuclear components. 



I wish here to thank Dr. A. P. Mathews for the very helpful 

 interest that he has shown in this investigation. 



