258 S. SAGUCHI 



2. It can not be said that the centrosome is always lacking in 

 case it can not be detected in the cihated cell. 



3. The centrosome may be situated in every level between the 

 nucleus and the cuticle. 



4. I have been able to find mitosis of the ciliated cells in in- 

 vertebrates only. 



C. AMITOSIS OF CILIATED CELLS 



Henry ('99, '00), Ach ('02), Wallengren ('05), Jordan ('13) 

 and others have noticed ciliated cells with two nuclei, which, 

 according to these authors must be a result of direct nuclear 

 division. I also found what appears to be amitosis of the cili- 

 ated cell in the following places. 



1. The intestine and hepatic. duct of Helix. Here often occur 

 ciliated cells with two nuclei (figs. 13, 14) which are oval in 

 shape; these cells also may contain, as usual, a centrosome con- 

 sisting of two granules, situated about midway between the 

 cuticle and the nucleus (fig. 14). On close examination of prepa- 

 rations it would appear that these two nuclei are produced by 

 direct nuclear division. In the middle of the nucleus there first 

 appears a transverse furrow (fig. 12) ; by the deepening of which 

 it becomes separated into two nearly equal parts. I have never 

 observed cases in which the division was effected by the stretch- 

 ing of the nucleus. Cell-division follows nuclear division; the 

 cell-boundary appears between the two nuclei; thus two super- 

 posed daughter-cells are produced, of which the upper alone 

 bears cilia, while the lower one becomes transformed into a basal 

 cell and then, by the accumulation of secreting granules in its 

 interior, into a glandular cell, which elongates upwards between 

 the ciliated cells until it reaches the surface of the epithelium. 



Besides cells with two nuclei, there are occasionally seen those 

 with three, four or five nuclei; even in these cases the internal 

 structure at first shows no noticeable change. Whether these mul- 

 tinucleated cells are capable of division is doubtful; in all like- 

 lihood one or several of the nuclei undergo degeneration later on. 



2. The pharnyx of Amphibia (Rana temporaria and esculenta, 

 Bufo, Triton). In the normal condition, the surface of the 



