762 



cular nuclei; it is thin over the greater part of the animal but at the 

 sides of the neural groove it thickens merging into a distinctly columnar 

 epithelium, the peripheral border of which stains strongly with Haema- 

 toxylen. 



Beneath the Syncytial layer a thin band of circular muscle fibres 

 is found and within these a number of isolated longitudinal fibres. 



The body wall in the region between two well developed individuals 

 is thrown into a series of longitudinal folds. 



The body cavity contains a large number of amoeboid corpuscles, 

 these in certain regions of the body seem to associate in a loosely reti- 

 cular tissue. 



The wall of the gut is composed of an outer layer of circular 

 muscles and a layer of digestive cells. 



^ N.C. 



C^ — • ■ — 



Int. Ph. ^ 



^T* 



^^• 



Fig. 5. Diagram of stock of Weldonia paraygucusis (A) and Microstoma lineare (B) 



showing relative positions of the pharynx, intestine and nervous system. 

 CM, Circular muscles; L.M, Longitudinal Muscles Fibres; Co, Corpuscle in Body 

 Cavity; Cic, Cuticle; Ep, Epidermis; G, Ganglia; Ini, Intestine; M.C, Muscle cell; 

 N.C, Nerve Cord; N.O, Neural Grroove; Ph. Pharynx; S.O, Sense organs; Sy, Syn- 

 cytial layer. 



These cells seems to possess a certain amount of amoeboid movement 

 at their internal periphery. 



The sense organs resemble the "ciliated pits" found in the lower 

 Turbellaria and consist of T shaped imaginations of the Epidermis. 



The Internal wall of the sense organ consists of the following 

 layers: — 



1) a layer of mucus. 



2) a layer of sensory (?) cells with large lightly staining nuclei. 



3) Ganglion cells. 



