Vol. l] Bovard. — Sense Orgams in Microscolex Elegans. 



271 



cuticle could be removed. They are very delicate and easily turn, 

 so ;is to insure removal without tearing the worm was cut trans- 

 versely into two pails and the cuticles handled with camel's 

 hair brushes. 'Phis is practically the same method used by Miss 

 Langdon ('95). They were then carefully spread out on slides 

 and allowed to dry. When thoroughly dry the cuticle sticks to 

 the slide and is ready to be examined. The spots which indicate 

 the areas of the sense organs are thinner than the rest of the 

 cuticle, and perforated with minute holes where the sense hairs 

 project. At best these areas are not clearly denned. Staining 

 the cuticle was tried with very good results, this bringing into 

 stronger contrast the sense areas and the remainder of the 

 cuticle. The staining was done before the cuticle was spread 

 on the slide. The cuticle was dipped into a strong stain two 

 or three times, rinsed with pure water and then mounted. A 

 few cuticles were stained after mounting, but on account of 

 their hardness when dry. they did not take stains well. 

 Nigrosin, iron haematoxylin, Ehrlich's haematoxylin and meth- 

 ylin blue were used. Nigrosin was the most satisfactory. The 

 staining of the cuticle is an important aid to accurate study of 

 the distribution of the sense organs. 



D 



Text Pig. 1. The small rectangles indicate the areas as 

 seen with the small diaphragm in the eyepiece of the micro- 

 scope. The arrows indicate the order in which the areas were 

 examiued. 



The plan was to count all the sense organs found in the 

 entire cuticle and to plot these so that their distribution in any 

 part might be seen at a glance. It was also desired that the 

 count of the sense organs should be as accurate as possible. In 

 order to see the sense areas well a high magnification was neces- 

 sary. Under these conditions a whole metamere could not be in 

 the field at once, so a method was devised whereby a small area 



