STUDIES ON CILIATED CELLS 241 



3) Neither rootlets nor granules are visible (Lenhossek, '98) 

 in the trachea of the rabbit; (Gurwitsch, '01), in the oviduct of 

 the rabbit; (Tschassownikow, '13), in the oesophagus of the 

 axolotl. 



I have been able to distinguish the following two plasma divi- 

 sions in all the cihated cells studied : 



a) Under the cuticle there is a dense, transparent zone (figs. 

 6-9, 42-45), which is marked off below from the cytoplasm 

 proper by a relatively distinct boundary-line. Apparently 

 it never is lacking in ciliated cells, though it varies greatly in 

 thickness. The rootlets of the cilia, arising from the basal cor- 

 puscles, pass through this zone (figs. 6, 54). Its existence was 

 noticed by Gurwitsch ('01) in the cihated cells of the pharnyx of 

 Bufo, of the intestine of Lumbricus and of the tela chorioidea of 

 Salamandra, and we also find the same in the figures of Heiden- 

 hain ('99), and Erhard ('10). As stated above, the basal bodies 

 are usually situated, either within the cuticle, or between this 

 and the transparent zone; they may occur occasionally within 

 the latter, as in the cihated cells of the tela of Amphibian larvae 

 (figs. 37, 38). 



b) The cytoplasm proper occupies by far the largest part of 

 the cell-body; it exhibits a reticular or alveolar structure and 

 contains a goodly number of mitochondria. 



The size and arrangement of the meshes of the protoplasmic 

 reticulum are not the same in different cells. We find a most 

 striking instance of the longitudinal elongation of these proto- 

 plasmic meshes in the ciliated cells of the intestine of Anodonta and 

 of the hepatic duct of Helix (figs. 6-11). In these cases the main 

 beams run vertically and pass through the transparent zone to 

 come into connection with the basal corpuscles. It is natural 

 that these longitudinal striae, which correspond to what is 

 described by various investigators as rootlets of the cilia, do not 

 run independently, but are connected with each other by minute 

 lateral fibrils. In this respect I agree entirely with Kolaev 

 ('10), who says: 



Aiif diese Weise entsteht das typische Bild eines etwas in die Lange 

 gezogenen Netzes mit Verdickimgen an den Knotenpunkten, wobei die 



