22 THOS. H. MONTGOMERY, 



ganglion cells of the lateral nerve chord, accordingly within the outer 

 neurilemmatic sheath. 



The amount and distribution of this pigment probably determines 

 the color variety (i. e. red or green). My preparations furnish the 

 following data on this point : 



a) Green variety: 7 individuals sectioned; 4 of these with 

 apparently no pigment, 3 with a small amount of pigment. 



b) Red variety: 4 individuals sectioned; 3 with a large amount 

 of pigment, 1 with very little pigment. 



None of the green individuals had as much pigment, as the red. 

 If it be permissible to draw conclusions from such meagre data, we 

 might consider the red color due to the greater amount of pigment, 

 and the green to the lack of it. But the red color must be due to 

 refraction of light rays coming from the greenish pigment. Further, 

 in both color varieties the dorsal side is darker than the ventral ; 

 and we have found the pigment most abundant on the dorsal side. 



3) The mesenchym tissue occurs very sparingly in this 

 species, owing to the great reduction of the body cavity. A remnant 

 of this cavity way, however, be found in the mouth region, between 

 the oesophagus and proboscis sheath, and is filled with a structure- 

 less, unstaining fluid (Fig. 30). In the latter occur bi- or multipolar 

 mesenchym cells, without membranes, and with oval, deeply staining 

 nuclei: each nucleus being imbedded in a mass of cytoplasm, from 

 which branching and anastomosing fibres radiate outwards (Fig. 26), 

 The exceedingly fine fibrous network found in the fluid of the cavity, 

 and which is densest in the neighbourhood of the cells, represents 

 sectioned terminal fibrils of the cell fibres. A small number of free- 

 floating cells are also situated in the fluid of the body cavity, which 

 are structurally similar to those just described, except that they are 

 devoid of fibres; in a few of them, evidences of amitotic cell division 

 are present. With one exception, in all the individuals examined no 

 trace of a body cavity was to be discovered in the posterior region 

 of the body, it being absent even in an immature individual of only 

 2 mm in length. Hence, there is in the posterior region also no 

 layer of mesenchym cells to be found, since the space there between 

 the intestinal wall and the inner longitudinal muscle layer is nearly 

 completely filled with the connective tissue elements, with inter- 

 cellular substance ^). 



1) I would note, in passing, that a special musculature is present 



