230 S. SAGUCHI 



3) According to Engelmann ('80), Gaule ('81), Carriere (82), 

 Heidenhain ('99) and others, the cuticle is provided with rod- 

 like corpuscles, which appear, in profile, as longitudinal parallel 

 striae, with the upper ends of which the cilia are connected; a 

 view which is not markedly different from that described under 

 2). 



4) Marchi (66) and Studnicka ('00) admit sieve-like perfora- 

 tions of the cuticle, through which the cilia pass downwards 

 into the cytoplasm. 



5) This view admits an alveolar structure of the cuticular 

 border. Gurwitsch ('01) finds that the cuticle, in surface views 

 of the ciliated cells from the rabbit's oviduct, is made up of 

 regularly arranged alveoh; at the nodes of the alveolar net- 

 works there are basal corpuscles, with which the cilia are con- 

 nected. Studnicka ('00) also found an alveolar structure of the 

 cuticle in the ependyma cells of Spinax niger. 



I have, in turn, found, in all forms studied, th the super- 

 ficial portion of protoplasm of the ciliated cell, that is to say, 

 the part where the cilia are implanted in the cell, is always, of 

 a denser character, appearing either as a crust or as a well- 

 defined cuticle, which varies greatly in thickness. 



Whether the longitudinal striation of the cuticular border, 

 seen in profile, is a feature brought about by the passage of the 

 cilia, or is owing to rod-like structures in the cuticle, or is an 

 appearance due to canaliculi, or is produced by an alveolar struc- 

 ture, of the cuticular border, is a question which is very diffi- 

 cult to solve; at least when one attempts to draw any conclu- 

 sion from the study of ciliated cells themselves, since the feature 

 is more complicated by the implantation of the cilia. I believe 

 that the clue to the solution of the problem is furnished by the 

 study, either of those cases in which the ciha are limited in a 

 certain circumscribed portion of the cuticle (e.g., in the epi- 

 dermis and tela of Amphibia-larvae), or in the transformation 

 of non-ciliated into ciliated cells, or in the redifferentiation of 

 ciliated cells into non-ciliated. From such studies 1 have been 

 able to find three types of differentiation of the superficial por- 

 tion in the ciUated cells studied: 



