STUDIES ON CILIATED CELLS 239 



1 have, in my turn, noticed in all ciliated cells studied, as the 

 product of differentiation at the distal cell-border, a crust or 

 striated cuticle pro\'ided with basal corpuscles or penetrated 

 by the cilia, but I have never seen rod-like corpuscles situated 

 on the outside of the cell-border. The cilia, from the basal cor- 

 puscles to their distal extremities, whether they are within or 

 outside of the cuticle, show no trace of structure, but appear 

 completely homogeneous. In the following I discuss the value 

 of the 'rod theory,' comparing my results with those of Engel- 

 mann and Frenzel. 



Engelmann ('80), (1) in his figures 11a and b, 12, 15, shows a 

 well-defined, homogeneous border on the row of his basal knobs; 

 (2) in his figures 5, 9, 18, and 19, a row of basal knobs, the upper 

 and the lower ends of which are defined by straight lines, so that 

 the appearance of a striated cuticle occurs; (3) in figure 20, 

 basal knobs arranged on the surface of a cell from the olfactory 

 pit of Rana temporaria ; the upper ends of these bodies are con- 

 nected, by means of intermediate segments, with the hair-bulbs 

 of the cilia. Thus Engelmann admits three types of implanta- 

 tion of the cilia. Is it rational to believe such a variety of 

 structure in cells which fulfill the same function? I will try to 

 account for this variety of structure in the following manner: 

 In the first case Engelmann's conclusions are nearly in agreement 

 with mine; for, in his figures, it is clearly seen that the cilia pass 

 through the cuticle superposed upon the row of basal knobs 

 which seem to correspond to my basal corpuscles. In the sec- 

 ond case the author, in all probability, saw a striated cuticle 

 with or without basal corpuscles. In the third case the cutic- 

 ular substance, for some reason or other, escaped his obser^^a- 

 tion, while the striae or the rod-like basal corpuscles, which 

 stand out sharply, he takes to be independent rods upon the 

 cell-border. The basal rods of Frenzel, on the other hand, seem 

 to be distinct from the basal knobs of Engelmann in shape and 

 refrangibility, as Frenzel says. I am rather, with Studnicka 

 ('99), of the opinion that the basal knobs of Engelmann corre- 

 spond to the lower knobs of Frenzel. The hair-bulb of the 

 above authors might be identified with the node produced by 



