386 MARGARET LEWIS NICKERSON. [Vol. XVII. 



Organs of the Second or Glmidular Class {First Type). 



The structures belonging to this class are rather small, glan- 

 dular bodies, containing a few — probably never more than eight 

 or ten — large gland cells, each of which is rudely pyramidal 

 in shape. Fig. 20 (PI. XXXV) represents a section through 

 one of these organs from a preparation made by the Vom Rath 

 method. Over the middle of the organ is a tubular excavation 

 in the outer surface of the cuticula, which probably represents 

 the common duct of the gland cells. Besides the large gland 

 cells, two nuclei are shown situated near the base of the organ, 

 and another lying close to the periphery of the upper portion 

 of the flask. These nuclei are best interpreted by comparison 

 with Fig. 5 (PI. XXXIV), which represents a section through 

 one of these same organs from a worm injected with methylene 

 blue. It is here demonstrated that sensory as well as glandu- 

 lar cells are present, and that the nuclei near the base of the 

 first figure, in all probability, correspond to the sensory cells 

 which are colored blue in the second. These cells are evidently 

 bipolar with a small cell body. They are situated near the 

 base of the organ, and in its central axis, or else close to the 

 limiting membrane of the organ, outside the gland cells. 

 The peripheral as well as the central process is evidently very 

 slender, and the small cell body is almost entirely occupied by 

 the nucleus. The exact method of termination of the periph- 

 eral process was not determined by this method, and indeed the 

 results of the methylene-blue staining were in all respects far 

 less satisfactory for this type of organ than for any one of the 

 other three types. This was probably due, in some cases, to 

 the fact that the glandular secretion was stained somewhat 

 diffusely with the blue and so tended to obscure the sensory 

 cells. In sections stained by the Vom Rath method the 

 nuclei belonging to the large gland cells were not visible, but in 

 sections from material treated with methylene blue and after- 

 wards stained by alum carmine a small round nucleus was 

 demonstrated near the base of each gland cell. 



Fig. 22 (PI. XXXV) shows one of these organs containing 

 about the maximum number of cells and presenting a condition 



