STUDIES ON CILIATED CELLS 253 



the ciliated cells which possess centrosomes always multiply by 

 means of mitotic decision, is another matter, which will be dealt 

 with separately in the next section. 



1. The intestines of Helix and Anodonta. The ciliated cell from 

 these organs contains a well-marked centrosome (figs. 6, 14, 15) 

 which is commonly situated between the nucleus and the cuticu- 

 lar border, either near the cell-axis or at the periphery of the 

 cell (fig. 6). It generally consists of two granules; the line of 

 connection between them being in most cases parallel to the 

 cell axis. They are surrounded with a clear halo, into which 

 chondriocontes never enter. In the ciliated cells of the typhlo- 

 sole of Anodonta, Erhard ('10) claimed to have found a centro- 

 some in the form of double granules immediately below the cuticle, 

 but the corpuscles in his figures 1, 11, and 12 are too indistinct 

 to be distinguished from the basal corpuscles in this region. 



2. The pharnyx of Hynobius larvae. Here the centrosome of 

 the ciliated cell is a double granule (fig. 55) between the nucleus 

 and the cuticle, especially near the latter and often near the 

 periphery of the cell. The granules are either equal or unequal 

 in size, and are surrounded by a halo. The line of connection 

 between them is usually vertical, but an oblique or even a hori- 

 zontal direction is not infrequent. I have also noted occasion- 

 ally a centrosome containing one, three or four granules. There 

 are descriptions of the central corpuscle of the ciliated cell in 

 the pharnyx of Urodela, by Studnicka ('99), Eismond ('00), 

 Fischel ('00), Gurwitsch ('01) and Tschassownikow ('13). The 

 first three authors state that the centrosome occurs in the form 

 of a diplosome between the nucleus and the cuticular border, 

 just as I have found it. Studnicka, in addition, noticed, in 

 the pharnyx of Salamandra, a centrosome consisting of three 

 granules. On the other hand, Gurwitsch figures a centrosome 

 in the superficial layer of a ciliated cell from the region interme- 

 diate between the pharnyx and the oesophagus of Salamandra* 

 an observation with which those of the above authors and of 

 mine are not in accord. 



3. The pharnyx of Bufo. The centrosome is situated above 

 and near the nucleus (fig. 49, the cell to the left), and consists of 



