330 ELEMENTARY BIOLOGY. [CHAP. 



c. Carefully snip away the membranous tissue at the 

 base of the labial palps ; there will thus be laid 



bare the cerebral ganglia. 



11 



Each is about the size of a pin's head, and 

 somewhat triangular in form; it lies immediately 

 in front of the protractor pedis tendon, and dis- 

 tributes fibres to the anterior adductor muscle, 

 labial-palps and pallial lobe. Examine, in connec- 

 tion with the one exposed 



a. the inter-cerebral com?nissure. 



A short cord uniting the two cerebral ganglia 



across the middle-line, above the gullet. 

 y8. The further course of the cerebro-splanchnic co?n- 



missure. 



Dissect off the fibrous tissue between the 

 anterior retractor and protractor tendons, anc 

 remove the body-wall, between these and th^ 

 anterior end of the pericardium. The commis 

 sure will be exposed, on carefully picking awaj 

 the superficial portions of the digestive am 

 reproductive glands along the same line. 



d. Remove a small portion of the body-wall along th< 

 point of origin of the muscular foot, and pick awaj 

 the genital gland until the pedal ganglia are reached j 

 they are a pair of deep-orange-coloured ov£ 

 bodies, each rather larger than a big pin's heac 

 applied to one another in the middle line, near the 

 point of junction between the body and the musj 

 cular foot. 



Branches are given off to the muscles of th( 

 foot and to the auditory organ. See infra. 



e. The cerebro-pedal commissure ; a cord which runs 



