Morr;h. C:l 



Body V/all 



The body wall of ueiaatodGs consists of cuticle, hypodorrtiis (epidermis, 

 subcuticle), and muscle layer. The cuticle (Plate II, Fig. 5j F) is 

 a non-cellular layer extended inward at the mouth, excretory pore, 

 vulva, and anus. It is intimately connected with and, undoubtedly, is 

 a product of the hypodermis. Histologically, it consists of several 

 layers ^^rhich are reducible to three kinds of material: the cortex , 

 the matrix , and the fiber layers . The cortical layer consists of a 

 dense material of the nature of a keratin and is resistant to solvents 

 and to digestion. The matrix layer, according to Chitwood (1936), 

 consists of, or contains, a fibroid named matricin, rich in sulphur. 

 The innermost part of the cuticle consists of tw^ or three fiber layers 

 of very dense connective tissue running: in different directions in 

 adjacent layers. These fiber layers consist chiefly of collagen. 



The hypodermis (Plate II, Fig. 5, G) is a syncytial layer that bulges 

 into the pseudocoel at four places to form four longitudinal ridges 

 terraed the longitudinal chords (Plate II, Fig. $, A, D, I), middorsal, 

 midventral, and lateral in position. The nuclei of the hypodermis are 

 confined to the chords. The nerves and excretory canals (when present) 

 are in these chords. Some forms may have more than four chords. 



The musculature of the body may be divided into two general types, the 

 somatic musculatuje and the specialized muscles . The somatic muscula- 

 ture is the general muscular layer of the body wall and is composed of 

 a single layer of obliquely arranged, more or less spindle-shaped cells 

 attached to the hypodermis throughout their lengths (Plate II, Fig. S, 

 H) . Specialized muscles, apparently of the sarae origin as the somatic 

 musculature, are limited to some particular part of the body, such as 

 labial muscles, somato-esophageal muscles, somato-intestinal muscles, 

 rectal muscles, and copulatory muscles. 



The Digestive System 



The mouth leads into the buccal capsule , very variable in size, shape, 

 and degree of differentiation in different nematodes. The buccal 

 capsule and its stiffenings often exhibit a triradiate arrangement, 

 corresponding with that of the esophagus. In some nematodes, espe- 

 cially rhabditoids, the buccal capsule is divisible into three sec- 

 tions: an anterior chamber enclosed by the lips, the vestibule pr 

 cheilostom j a middle and longest and most sclerotized portion, the 

 protostom,- and a small terminal chamber, the telostom (Plate II, I'ig. 

 2). The walls of the various parts of the stoma are called rhabdions 

 and are termed cheilorhabdions, protorhabdions, and telorhabdions, 

 respectively. 



In certain groups of nematodes, the buccal capsule is armed with a 

 conspicuous protnasible s pear or stylet , used to puncture plants and 

 animal prey. This may be forme.i, as in tylenchoids, by the coming 



