STRUCTURE OF THE CHROMATROPE 



405 



purple) located definitely with reference to nerves, these nerves them- 

 selves so located as possibly to be sensory. 



SPECTROSCOPIC TEST OF THE PRESUMPTIVE CEPHALIC CHROMATROPE OF 



Mermis subnigrescens 



One-third of a millimeter of the front end of an adult female Mermis 

 subnigrescens, including the head, was ligated and cut off, and then 

 mounted on a microscope 

 slide in water. The head 

 was examined under a 1.5 

 mm. apochromatic micro- 

 scope objective, having a 

 similar objective as a con- 

 denser, in such a way that 

 the image would fill as much 

 as possible of the micro- ^f fit 

 scope field with the color of 

 the pigment. (See Fig. 1.) 

 The microscope was fitted 

 with a spectroscopic eye- 

 piece. 



Sunlight was taken from 

 a flat planished aluminum 

 reflector placed so that a 

 maximum of sunlight was 

 reflected through both in- 

 struments,^., the above 

 apochromatic-micro -spec- 

 troscope and a comparison 

 spectroscope. The pig- 

 mented tissue was brought 

 into focus, and then the iris 

 diaphragm of the micro- 

 scope thrown open, so as 

 to admit a "flood" of light. 

 This produced a spectrum 

 fairly readily seen in a 

 darkened room, notwith- 

 standing the very high 

 magnification. 



Much of the violet end 

 of the spectrum (well into 



X200 



Figure 1. Head end of Mermis subnigrescens, 

 showing the chromatrope. os, mouth; ppl (2), the 

 two lateral so-called "papillae;" amph, amphid; 

 nrv chrtrp, nerves of the chromatrope; lum oesoph, 

 lumen of the oesophagus; pgmt rub, reddish pig- 

 ment of the chromatrope; chrd md, median chord; 

 annnrv, nerve-ring; msc, body-wall muscles; cut, 

 cuticle; oe, oesophagus; ppl subm (4), the four 

 submedian papillae; nrv amph, nerve of the 

 amphid; ar mcrscp, shows the circular area of the 

 microscopic field that was tested spectroscopically ; 

 pgmt lut, orange-colored pigment of the chroma- 

 trope; chrmtrp, chromatrope; chrd lat, lateral 

 chord; sub cut, the thick subcuticle; crbrm, the 

 cerebrum; trphsm, anterior end of the trophosome. 



