170 TEE BIOLOGY OF AN ANIMAL. 



scissors. Observe the pulsations of the dorsal vessel 

 and of the aortic arches. 

 f. With a lens observe 

 a. Dorso-lateral vessels. 

 ft. Yentro-lateral vessels. 

 y. Supra-neural trunks. 



. Sub-neural trunk seen through the nerve-chain. 

 e. The beautiful red capillary network extending over 

 the body-wall, dissepiments, etc. 



3. In the same specimen work out the nephridia. 

 a. Study in situ with hand-lens. 



1}. Dissect out a number (half a dozen or more) of entire 

 nephridia with fine forceps and scissors. Mount in 

 normal salt solution, and examine with -J-inch obj. 

 Observe the ciliary action and the various portions 

 of the nephridium. 



c. Remove a number of nephridia from a preserved speci- 

 men, stain with borax-carmine or alum-carmine (un- 

 der the direction of the demonstrator), and mount 

 in balsam. Study carefully with low and high 

 powers. 



4. Lay open a preserved specimen, dissect away the alimentary 

 canal behind the pharynx, and expose the ventral nerve-chain. 

 Observe 



a. The ganglia and their connecting commissures. 

 l>. The lateral nerves. 



c. Trace the chain forwards to the oesophageal collar; 



notice the lateral nerves at this point. 



d. Follow the collar around to the dorsal side of the 



pharynx, and observe the cerebral ganglia and their 

 nerves. 



e. In a large preserved specimen make out the pharyngeal 



ganglia. 



f. Cut open a preserved worm on the dorsal aspect and 



soak in 10$ nitric acid for several days (i.e., until 

 thoroughly macerated). The entire nervous system 

 can then be easily removed, and after cleaning and 

 dehydration, etc., may be mounted in balsam. The 

 specimen should not be stained. 



5. In a freshly killed and opened worm (preferably in June), 



