5 66 



APPENDIX 



b. In the worm, note the following structures exposed by 

 removal of the alimentary canal : suprapharyngeal ganglia, 

 circumpharyngeal commissures, subpharyngeal ganglia, 

 ventral nerve cord ; spermathecse, vesiculae seminales, 

 ovaries ; nephridia (Figs. 139, 146). 



Open another worm under normal salt solution, 

 loa. Remove a nephridium with the part of the septum in front of 

 it to which it is attached, mount it in salt solution, and 

 examine it under the microscope. Note : nephrostome 

 (Fig. 141) ; various portions of tube with capillaries (Fig. 

 142 and Plate XVII.). Small, parasitic nematode worms 

 will probably be seen. 



Remove and mount an ovary (Fig. 145). 



Mount contents of a vesicula seminalis. Examine alive, 

 fix with a drop of absolute alcohol, stain with picrocarmine 

 <P- 554)> an d examine. Observe stages of development of 

 spermatozoa (Fig. 406). 



dA-K ht. 



*-•+ 



Fig. 405. — A diagram of the principal blood vessels of the earthworm. 



d.b.v., dorsal blood vessel; hi., one of the "hearts"; int., intestine; ?«., mouth; 

 as., oesophagus; par.v., parietal vessel; ph., pharynx; sup.6h.g:, supra- 

 pharyngeal ganglion; s.i.v., subintestinal vessel; s.rt.v., subneural vessel; 

 v.n.c, ventral nerve cord. 



Mount and examine contents of a spermatheca. Examine 



and note ripe spermatozoa (Fig. 406). 



b. Examine under low power a transverse section of the intestinal 



region. Note ; in body-wall, cuticle, epidermis, and circular 



and longitudinal muscles ; cceloni ; in gut-wall, lyphlosole, 



yellow cells, muscular layer, endoderm ; nerve cord ; dorsal, 



subintestinal, and subneural blood vessels ; nephridia ; sette 



(Fig. 136). Examine portions of the section under high 



power (Plate XVII.). 



Longitudinal sections of the earthworm are difficult to interpret 



because the worm is never quite straight when it is cut, and because 



the contents of the section vary with the distance from the middle line, 



but there may be found in them, besides the body-wall, some or all 



the regions of the alimentary canal, septa, vesiculoe seminales, and 



usually portions of the dorsal blood vessel, ventral nerve cord, and 



suprapharyngeal ganglia (Fig. 137, diagram). 



