42 PRACTICAL ZOOLOGY. 



5. Observe the muscular partitions between the seg- 

 ments ; what is their relation to the intestine ? Care- 

 fully compare the partitions with the external mark- 

 ings and the sets of spines. Are there as many seg- 

 ments as are indicated by the external appearance? 



6. The brownish substance along the top of the intestine 

 is the liver. 



7. Continue the cut to the anterior end, being very 

 careful not to cut the intestine, especially in the part 

 anterior to the girdle. Pin well out. Cut the parti- 

 tions down at the sides, to free the inner structures. 



8. In the region of the tenth segment are several roundish 

 white bodies, — reproductive organs. 



9. Alternating with these are several red masses. These 

 are side branches of the dorsal blood-vessel, which 

 curve downward on each side of the gullet, to unite 

 with a ventral blood-vessel, thus forming rings around 

 the slender gullet. These rings have enlargements, 

 thus resembling necklaces. 



10. Back of the reproductive organs are two enlargements 

 of the digestive tube, different from the intestine. 

 The foremost of these is the crop, the hinder is the 

 gizzarck 



11. In the first six segments is a wide portion of the 

 digestive tube, the pharynx. Carefully dissect away 

 the thick muscular partitions, to see it more clearly. 

 This pharynx is used as a proboscis, being protruded 

 from the mouth and inverted. 



12. The pharynx narrows behind into the gullet. Trace 

 this back under the reproductive organs to the crop. 

 The gullet is the narrowest part of the digestive tube, 

 and if the reproductive bodies have been sufficiently 



