388 MARGARET LEWIS NICKERSON. [Vol. XVII. 



by the Vom Rath mixture, the cell body with its characteristic nu- 

 cleus can be distinguished readily as that of a nerve cell, although 

 neither process of the cell can be followed for any distance. 



Besides these sensory cells, each organ contains a large num- 

 ber, often as many as twenty or thirty large gland cells, each of 

 which is broadened at the base and narrowed somewhat toward 

 the outer end. The nucleus lies near the base of the cell, and 

 above the nucleus is an intracellular ampulla opening into a 

 canal which unites with similar canals coming from the other 

 gland cells of the organ. By the union of all these canals a 

 duct is formed which communicates with the exterior by means 

 of a pore in the cuticula situated over the summit of the 

 organ (PI, XXXV, Fig. 15). As the sacks are nearly always 

 plump, it is inferred that they are filled with a fluid secreted 

 from the gland cells, although the sack contents were unaffected 

 by any of the stains used. 



So much may be said in the way of a general description of 

 these organs ; but for a correct understanding of the individual 

 cells and intracellular structures, the various conditions pre- 

 sented by the different phases of activity must be noted. At 

 what is probably a comparatively early stage in the activity of 

 one of these gland cells, there are present outside each of these 

 membranous sacks a very large number of delicate radiating 

 threads which form a rather broad radial zone or vesicle be- 

 tween the sacks and the general cytoplasm of the cell. These 

 threads are attached by one end to the sack wall, and are lim- 

 ited at the other end by the general cytoplasmic reticulum, with 

 which they are probably continuous. The width of this radial 

 zone may be equal to that of the sack (PI. XXXV, Fig. 16). 



A condition considerably later than the one described is 

 shown in PI. XXXV, Fig. 17. As figured here, there appear 

 to be large vacuoles in the protoplasm, which in some cases 

 occupy nearly the whole of the cell. The sack within now 

 almost or quite fills the vacuole, and the delicate threads shown 

 in the first figure are not visible in case of the enlarged sacks. 

 The ducts from the different sacks unite as before and finally 

 form a single tube. In the case of two of the cells the con- 

 dition shown in the first figure is retained. Other organs show 



