146 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



a. Cut the dorsal vessel, and place a drop of the red 

 fluid on a slide ; note that it coagulates quickly. Cover 

 another drop, and examine with a microscope. It is a 

 clear, red fluid, which contains small, flattened, oval or 

 fusiform colorless corpuscles, much smaller, and with 

 sharper, more regular outlines than those from the body 

 cavity. 



The digestive tract may now be cut ofi" posterior to the 

 pharynx, and removed from the body, in order to expose 

 the organs which lie below. Great care is necessary to 

 avoid injuring the testes while removing that part of the 

 oesophagus which lies between them. 



If a fresh specimen has been used, it should now 

 be covered with strong alcohol, in order to coagulate 

 and harden the delicate transparent portions of the 

 body. 



7. The nervous system. This is made up of: — 



a: The cerebral ganglia, which, as has been pointed 

 out, are situated upon the dorsal surface of the pharynx 

 in the third segment (Fig. 84, a; Fig. 84, K). 



(i.) A large nerve may be traced forward from each 

 half of the cerebrum (Fig. 87, i). These nerves soon 

 divide into smaller branches, which pass to the anterior 

 segments, especially the first. 



(ii.) From the outer ends of the cerebrum two com- 

 missures (Fig. 87, d,) pass outward and downward around 

 the oesophagus to unite with the ventral chain. 



(iii.) Four or five nerves may be seen to run backward 

 from the upper portion of each half of this collar (Fig. 

 87, g). They soon penetrate the muscular walls of the 

 pharynx, and their terminations cannot be made out with- 

 out further dissection. 



