1896 THE MICROSCOPE. 3 



alternate and sometimes they are regular in the anterior 

 part and alternate in the posterior but the ventral line 

 usually remains the same throughout the body. 



In figure 5, the worm is represented as having been 

 cut down the back and laid open. The heavy lines (f) 

 represent the divisions between the segments, while g 

 represents the smaller divisions of these segments. No- 

 tice how many more small divisions there are in the first 

 twenty segments from the head. This is the part which 

 contains the vital organs and below these there are usu- 

 ally two lines of division only. This figure also shows 

 the position of the setse (figure 5, s,) and of the nephri- 

 dia or breathing pores (figure 5, n). 



Now take the first five or six segments, soak in a little 

 liquid potassse, wash and press between two slides. One 

 will probably be able to see the pharynx (figure 7, b) 

 but certainly the strong muscles which move the head 

 (figure 4, a). Take another head, cut it down the 

 back and lay it open on the slide, then press. The septa 

 or large muscles which move the body (figure 4, b) may 

 be seen and sometimes the smaller ones (figure 4, e) ; but 

 in nearly all specimens whether open or not little red 

 conically shaped projections may be seen. These are 

 the nephridia (figure 4, d). There are usually two of 

 these in each segment and they are connected with a 

 bunch of tubules (figure 4, e). The worm has a gland 

 which answers the purpose of a heart and has a nervous 

 system; figure 4 f shows the position of tlie cerebral 

 ganglion, the principal gland of this system. 



The digestive apparatus is divided into pharynx, oeso- 

 phagus, gizzard and intestine. The food is taken into 

 the mouth, thence it goes into the pharynx (figure 7, b), 

 from there through the oesophagus (figure 7, c), and a 

 portion of the intestine into the two-lobed gizzard (figure 

 7, d and e). From the gizzard the food passes through 



