GENERAL BIOLOGY 



trace the nerve cord anteriorly to its division into right and left 

 halves which pass around the digestive tract to form a ring which 

 unites with the brain on the dorsal side of the pharynx. 



3. Brain ; connected as above shown with the ventral nerve 

 cord, but lying dorsal to the pharynx. Note the nerves given off 

 from the brain and also from the connectives on the side of the 

 pharynx. 



Make a drawing of the nervous system. 



VI. BODY WALL. 



Pin out part of the body wall quite flat and note that the mus- 

 cular layer of the wall is interrupted along four longitudinal lines 

 in which are the setae in sacs or setigerous glands ; four of these 

 occur in each somite. Between somites 12 and 13 some of these 

 glands are conspicuously large; tease out one and note under 

 the microscope the color, shape and hardness of the setae. 



C. ANATOMY AND PHYSIOLOGY OF LIVING SPECI- 

 MENS. 



I. MOVEMENTS. 



1. Place a worm upon moist filter paper and observe the direc- 

 tion and method of movements. 



2. In small light-colored worms note the contraction of the 

 dorsal blood vessel and the movements of the blood toward the 

 anterior. 



3. Gently touch different parts of the body and note which are 

 the most sensitive. 



4. Place the worm under a glass vessel with some cotton satur- 

 ated with chloroform, the vapor of which will render the animal 

 insensible ; when motion has ceased remove the worm ana cut it 

 open as in the specimen previously dissected, but only in the an- 

 terior region and a little to one side of the median line. Keep the 

 specimen wet with physiological salt solution. 



II. VASCULAR SYSTEM. 



If the specimen is not quite dead observe : 



a. The contraction of the hearts, dorsal vessel, and sub-neural 

 vessel ; in the latter the wave of contraction passes backward. 



b. Small blood vessels passing from the dorsal vessel to the 

 digestive tract, and from the ventral vessel to the body wall and to 

 the septa. 



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