BUSYCON 147 



a little to the right and anterior to the anus. If possible, 

 insert a guarded bristle into this opening and see what be- 

 comes of it. Trace the oviduct from the ovary along the 

 columellar side of the liver. See what becomes of it. Ex- 

 amine the inside of the nidamental gland and see its relation 

 to the oviduct. 



If the specimen is a male, follow the vas deferens from 

 the testis to the base of the penis. 



Circulatory System. — Remove the thin membrane that 

 forms the roof of the pericardial chamber. 



1. The heart consists of: (a) the large, rounded ventricle; 

 (£>) the smaller, conical, thin-walled auricle. 



2. The auricle receives blood by two vessels. One, return- 

 ing blood from the gill, runs along the left side of the gill to 

 its posterior end, where it bends abruptly to the right along 

 the margin of the pericardial cavity, and enters the auricle. 

 The other returns blood from the tubuliferous portion of the 

 kidney and follows the right side of the pericardium to the 

 auricle. 



3. The gill receives its blood through a vessel that borders 

 its right side. This vessel receives the blood from a portion of 

 the mantle, and from the large, acinous portion of the kidney. 



4. The blood leaves the ventricle by a single vessel, the 

 aorta, that almost immediately gives rise to the visceral 

 artery which supplies the visceral hump. Trace its distribu- 

 tion. 



The aorta makes an abrupt turn downward and forward 

 and enlarges to form the secondary heart which lies alongside 

 the esophagus. The course of this vessel can be studied best 

 after the completion of the work on the nervous system. 



The course of general circulation is, beginning with the 

 heart, (a) system, (£>) kidney, (c) gill, and (d) back again 

 to the heart. What is the advantage of such a course of 

 circulation over the reverse? 



Draw a figure showing the vascular system. 



Excretory System. — The two portions of the kidney have 



