114 F. H. STEWART. 



common. They generally lie opposite the longitudinal lines, 

 but also occur opposite the muscle fields. They resemble the 

 nuclei of the Type 2 epidermal cells, staining diffusely with 

 basic dyes, measure "00215 to '00822 mm. in diameter — that 

 is, rather smaller than the nuclei of Type 2. I have not been 

 able to find any protoplasm surrounding". They are completely 

 isolated from the epidermis by the fibrils. 



In the region of the collar, owing to the presence of the 

 ganglionic cells, the tissue is not so much developed (PI. 7, 

 figs. 3 and 4). Its characteristics are the same as already 

 described, but as it forms a stroma for the collar cells, the 

 general direction of the fibrils is rather parallel with the body- 

 surface than radial, since these cells are growing in from the 

 epidermal lines across the muscle fields. 



In front of the collar the tissue is still less developed, but 

 other tissues, such as the body-wall, are also somewhat meagre 

 as they approach the pharyngeal region. 



I believe that this fibrillar network has a very definite 

 function — viz. that of connecting the outer surface of the 

 oesophagus with the body-wall and affording a surface of 

 origin for the oesophageal muscle, so that when this contracts 

 the entire value of the contraction is devoted to widening the 

 lumen. In parasitic forms a similar surface is provided by 

 the thick cuticle which surrounds the oesophagus. 



Throughout the greater part of the intestinal region, owing 

 to the close approximation of the gut and body-wall, and 

 to the presence of the gonads, the space is narrow. The 

 substance filling it is best studied in the interval, triangular 

 in cross section, between the gut, body-wall, and gonad tube, 

 or where the gonad tubes end, but it must not be imagined 

 that it is confined to these regions, since it forms a complete, 

 although narrow, cylindrical covering for the gut. 



In sections through this region stained with thionin and 

 eosin (PI. 7, figs. 14, 15) a dull-pink hyaline ground-Avork 

 occurs with a very fine, more intense pink, granulation. The 

 very fine, obscure fibrillation which is found in the protoplasm 

 of the epidermis or of the gonad lube-wall is not present. 



