LUMBRICUS. 77 



somite, one nephridium on either side of the alimentary canal. 

 (The first three or four somites are not provided with nephridia.) 

 Each nephridium is a coiled tube, appearing to the unaided 

 eye as a fluffy mass, that opens externally between the groups 

 of setse, in the position already observed, and internally by a 

 small opening, the funnel. The inner opening is not in the 

 somite in which the most of the tube lies, but in the somite 

 anterior to it. That is, the nephridium that occupies the space 

 in somite twenty, opens externally on somite twenty, but in- 

 ternally perforates the septum directly anterior and opens into 

 somite nineteen. 



2. Remove a nephridium with your forceps and examine it 

 with your microscope. Notice that it consists of a coiled tube 

 of varying diameter. The funnel is not easy to find and is hard 

 to remove. It may be found by removing the portion of the 

 septum through which the nephridium passes and examining 

 it with a microscope. 



Draw the nephridia into your previous figure. 



Cut the stomach-intestine behind the gizzard and pull it 

 forward, carefully separating the tissue from it as it is drawn for- 

 ward, so underlying organs will not be disturbed. In this way 

 free the alimentary canal to the position of the pharynx. 



You can now see the extent of the nephridia, and possibly 

 see where they perforate the septa. 



Reproductive System. — 1. The seminal vesicles are large 

 white bodies, united in the median line. They send three lobes 

 on either side, that normally overlap the posterior part of the 

 esophagus. In what somites do the lobes occur? 



2. Carefully open the seminal vesicles near the median dor- 

 sal line and examine their contents microscopically. 



3. With a pipet wash out the contents and notice the two 

 pairs of convoluted funnels, the inner openings of the vasa defe- 

 rentia. The testes are hard to find, as they are the same color 

 as the coagulated mass that filled the seminal vesicles. They 

 are attached to the septa just anterior to the funnels. The 



