128 THE MICROSCOPIST. 



In dissecting the heart or dorsal vessel, the body must be 

 opened from the ventral surface, all the viscera removed, and 

 the vessel left with its ligaments attached to the upper rings of 

 the body. Or the superior segments of the body may be re- 

 moved by cutting with scissors along the lateral membranous 

 bands and removing all the upper part of the abdomen. The 

 dorsal vessel may then be slit open. This dissection requires 

 much care and great steadiness of hand. 



5. The muscular system of insects is very extensive. Lyonet 

 dissected and described 4061 in the caterpillar of the goat moth 

 {Cossus ligniperda). M. Straus-Durekheim and others recom- 

 mend that the insect should be cut in two a little to the right 

 or left of the median line, so that the half to be examined shall 

 be a little larger than the other, that the azygos muscles, &c., 

 in the centre be not injured. Beginning then with the internal 

 profile, layer after layer of muscles should be dissected. 



By previous maceration in dilute alcohol the muscles are 

 slightly hardened. If left too long, however, they will become 

 detached from the integument. 



