162 



LOCUSTS, BUTTERFLIES, BEES, WASPS 



Brain gant/U/i 



nately contracting and expanding movement of the abdo 

 men called the respiratory movement." 



The circulatory system of the locust. — The blood vessels 

 and the circulation of the blootl m in.sects are ^\■eU shown 

 by a study of tlie locust. The circulation of insects is not 

 well developed. The only blood ves.sel in the locust, for 

 example, is a long, slender, tubular organ that runs along 

 the dorsal side of the body cavity in the abdomen and 

 thorax and extends into the head. This is known as the 

 dorsal vessel, and tliat part of it lying in the abdomen is tlie 

 heart, while the anterior part, in the tliorax, is the aorta. 

 The heart is clo.sed at its posterior 

 end, but has openings along each 

 side through which the blood enters 

 Thomcic and, by contractions of the heart, 



{/"".'J'" ^^ forced forward tlirough the aorta 

 into the head. Valves within the 

 heart prevent the blood from flow- 

 nerrtToni nig bacKwai'd through it. ihe 

 blood is usually a colorless licjuid 

 and fills all the spaces of the body 

 cavity, literally bathing the tissues 

 and organs of the in.sect. It does 

 not cany ox3'gen liecause this is 

 done by the air tu]:)es. Its func- 

 tion is to cair\- the products of di- 

 gestion from the alimentary canal. 

 The nervous system, — The brain 

 consists of til roc 



^Abdominal 



f/WUlli(t 



arge ganglia 



101. — Ncr\"oiis ,^^^s 

 uf agrasHliopj..^. 



closely connected and lying above the gullet in the head. 

 From the brain the nerve cord ]iasses posteriorly, one 

 stranti going tlown the left side of the gullet and the other 



