62 THE EARTHWORM. 



small pores not seen so easily as the inale 

 apertures, their lips not being tumid, 

 iii. The apertures of the spermothecae or receptacula 

 seminis, of which there are two pairs, are 

 situated in the grooves between the segments 

 and in the line of the outer row of setae, the 

 first pair between segments ix. and x., the 

 posterior pair between segments x. and xi. 



d. The excretory apertures are best seen in a specimen 



which has been hardened in spirit, and dried with 

 a cloth immediately before examination. Each 

 segment, except the first three and the last, has 

 one on each side, either on the ventral surface a 

 little in front of the outer seta of the inner double 

 row, or, in some segments, high up on the side 

 of the animal. 



To see these apertures, strip off the cuticle from the 

 anterior part of the worm, and examine the worm with a 

 pocket lens, squeezing it slightly so as to cause fluid to 

 exude from the apertures. 



e. The dorsal pores, though small, are often visible to 



the naked eye. They open mid-dorsally in the 

 grooves between the segments, and place the 

 ooelom in communication with the exterior. 



The first one is between segments x. and xi. 

 and opens into segment xi. Behind this point 

 they occur regularly in every intersegmental 

 groove. 



II. DISSECTION OF THE EARTHWORM. 



Extend the animal under water with the dorsal surface 

 ■upwards, fixing it down by two pins through the sides of the 

 fourth segment and two near the hinder end. Cut through 

 the body-wall from end to end, close to the mid-dorsal line. 

 Gently raise the flaps with the forceps, and note the trans- 



