THE MITOTIC CYCLE 



The pulsations of the contractile vacuole cease during anaphase, and 

 are resumed in telophase. In Amoeba proteus during metaphase, fluid 

 is actually reabsorbed from the contractile vacuole into the cytoplasm 



(ChALKLEy280^). 



Within the intestinal epithelial cells of the frog, the secretory granules 

 disappear during mitosis (Cohen and Berrill^^b). The long filamen- 

 tous mitochondria of fibroblastic cells in tissue culture are changed into 

 short rods; in the malignant cells studied by Ludford et alii^^^ the 

 mitochondria are normally short, but they become granular after the 

 nuclear membrane has broken down at the end of prophase. At that 



Telophase 



Figure 49 Early telophase in Holomastigotoides tusitala x 2100. From 



Cleveland^'* {By courtesy. Trans. Amer. Phil. Soc). Showing separation of 



daughter nuclei by the unravelling of the 5th spiral band, to which s 



attached the smaller nucleus. 



time, according to these authors, the mitochondria 'are seen to have a 

 peripheral layer of nucleic acid. The cytoplasm itself contains little or 

 no absorbing material. It appears to have been deposited on the sur- 

 face of the mitochondria'. In dividing cells of several tissues, Dal- 

 -fON^si^ finds that the mitochondria decrease in either number or 

 size during prophase or metaphase. The osmophilic Golgi material 

 disappears entirely in hepatoma cells during mitosis. In the pollen 

 mother cells of Lilium, the cytoplasmic lipoidal granules aggregate 

 during metaphase (Sakamura;282 Kato^^^). Similar changes are des- 

 cribed by Pekarek^^^ in the cytoplasm of the end-cell of the rhizoid of 



134 



