338 GENERAL BIOLOGY 



The continuation of the mouth leads into the short curved oesopha- 

 gus which in turn leads to the large ingluvies ( ) or 

 crop. Here are seen various rows of spine-like teeth. The proventric- 

 ulus or gizzard ( ) follows. This is a very small 

 organ also furnished with spines ; it empties into the large, thin-walled 

 ventriculus or stomach. Six tubular gastric caeca or blind sacs are at- 

 tached to the anterior end of the stomach. Posterior to the stomach the 

 alimentary canal forms the intestine, which is divided into three por- 

 tions : the ileum ( ), rather slender, with longitudi- 

 nal ridges on the inside (the infolding ridges increase the absorbing sur- 

 face) ; the colon, smaller than the ileum and possessing a smooth lining, 

 and the rectum, which has six longitudinal rectal glands of unknown 

 function. 



The food of the red-legged locust, which feeds quite freely by day 

 (unlike the crickets and katydids which are more active at night), con- 

 sists of grass and little drops of dew. The pads at the tips of the legs, 

 and the claws, enable the animal to climb stalks of all kinds very readily. 

 This eating of dew rather than drinking at pools of water, has given us 

 the idea that there is something about standing-water that is fatal to 

 the grasshopper. That this idea is correct is evidenced by the fact that 

 grasshoppers kept in captivity must be sprinkled- with drops of water or 

 they usually perish. 



The food once taken in the mouth finds the salivary glands pouring 

 their secretions forth which thus assist in preparing the food for the 

 crop to which it passes through the oesophagus. Here it is mixed with a 

 molasses-colored digestive fluid. It then passes on, being again ground 

 by the spinous processes in the muscular gizzard. The various gastric 

 caeca, each of which has an anterior and a posterior pocket, increase the 

 stomach space. 



Once the food has passed through this stage it must become part 

 of the blood of the grasshopper. This it does by being absorbed through 

 the walls of the alimentary tract. 



f THE CIRCULATORY SYSTEM 



The grasshopper has a long tubular heart (Fig. 214, E) lying along 

 the dorsal surface just beneath the body wall. From this there are 

 arteries and sinuses connecting the various parts of the body. From its 

 position the heart is often called the dorsal vessel. 



Anteriorly the heart is prolonged into a tube leading to the head and 

 is partially divided by valves into eight chambers. The position of the 

 heart-valves allows blood to flow headward only. 



The propulsion of the muscular heart sends the blood forward 

 through various sinuses so that every part of the body may be nourished 

 by it. It then returns by a closed tube, the ventral sinus, to the peri- 

 cardial sinus or chamber, and enters the heart through several pairs of 



