THE GRASSHOPPER 339 



lateral ostia ( ). If more food has been absorbed 



than can be used, it is stored up as fat in the fat bodies on either side 

 of the heart. 



THE RESPIRATORY SYSTEM 



The blood of all insects (Fig. 220) contains a respiratory protein, 

 hemocyanin, similar to that of the crayfish. In some few species 

 (bloodworms=midge larvae, Chironomidae) hemoglobin is also found. 

 Since the hemocyanin is capable of absorbing oxygen and carbon dioxide, 

 it is probable that in the insects this respiratory protein aids the tracheae 

 in distributing oxygen and collecting CO 2 . The tracheae are kept open 

 and extended by a spiral thickening of chitinous lining and extend to all 

 parts of the body, even including the legs and wings (Fig. 215, B). 



This is, no doubt, one of the reasons why the circulatory system is 



i so poorly developed, for, unlike the 

 >O\ higher forms of animal life where 

 >^ the circulatory and respiratory sys- 

 * terns are dependent upon each other, 

 the systems in the insects are sepa- 



Fig. 220. Blood Corpuscles of the Grasshop- J 



per, stenobothrus. rate and distinct, so that everv part 



JceHne; of the body can be supplied with 

 showing nucleus. (After Graber). oxygen at any time, regardless of 



what may happen to another part. The disadvantage of such a method 

 consists in the necessity of having both a respiratory system and a cir- 

 culatory system in every part of the body, instead of having all respira- 

 tory work done in one place. The air sacs with which the tracheae are 

 connected are of value in making the animal light for flying and jumping 

 purposes. The grasshopper can beat any professional human jumper by 

 the distance it covers in a single leap when comparative size is con- 

 sidered. 



If one notices a grasshopper when it breathes rapidly, it will be seen 

 that the abdomen lengthens and shortens, thus forcing air in and out of 

 the spiracles on the thorax and abdomen. 



THE EXCRETORY SYSTEM 



Like all animals, the grasshopper needs oxygen to carry on its meta- 

 bolic processes, and like all animals gives off carbon-dioxide as a waste 

 product, as well as water and a nitrogen-containing-substance called urea 

 (if in solution) or uric acid (if crystalline). It is interesting to note that 

 those grasshoppers which live in dry places excrete the crystalline 

 product while those which live in damp places excrete the soluble form.* 



These excretory products leave the body through the urinary or 

 Malpighian tubules which empty into the intestine just posterior to the 

 stomach, thus causing both the excreted and egested material to leave 



*Doubt has been thrown on former investigations by recent work, so it is well not to assume 

 that our opinions in regard to the work of the Malpighian tubules or of the formation of urea 

 are final. 



