THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



Vol. XIV. JANUARY, 1893. No. 1 



The Grasshoppor. (Edipoda Carolina ; an Introductory 

 Stml.v in Zoology. 



By II. L . O S n O R N , 



ST. PAUL, MINNESOTA. 



(Continued from vol. xiii, p. 2S2.) 



[with frontispiece.] 



3. T'he respiratory system in the grasshopper is entirely un- 

 like that familiar to us from a knowledge of the backboned animal. 

 They breathe by means of gills or lungs. That means that blood 

 is brought by the circulatory vessels to an organ where its gases 

 have access to air, either fiee, as in a lung, or dissolved in water, 

 as in a gill, and it is also understood that these gases of the blood 

 have come from the organs, and the gases of the air are to be car- 

 ried to the organs. It is really in the organs that the uses of the 

 gases take place. It would, of course, then be possible to have 

 air conducted direct to the organs which use its gases, and this is 

 the fact in the grasshopper's system. The system consists of sur- 

 face holes, spiracles (Fig. 3), which admit air to main longitu- 

 dinal pipes, trachecE^ from which smaller and smaller branches, 

 which run out into every active portion of the body, carry it to and 

 from the organs. The final air pipes are microscopic, and spread 

 out so as to reach every active portion of the body. The principal 

 gas used by the organs is oxygen, and the principal ones given ofl 

 from the organs are carbonic acid gas and aqueous vapor. Un- 

 less oxygen is constantly carried in, and carbonic acid as constantly 

 carried out by the tracheae, the organs at first become sluggish, 

 and finally dead. 



4. The excretory system (Fig. 5) is composed of organs 

 whose work is to remove another product which collects in active 

 organs. It is called urea. The urea, the carbonic acid gas. and 

 the watery vapor are formed in working organs as a product 

 which results after the chemical union between the oxygen and 

 the substance of the working part. The power of the working 

 part comes from this chemical union, and the part tends 

 to burn out somewhat in the act, like fuel in a furnace, 



