PHYSIOLOGY OF THE ORTHOPTERA. 8 1 



of the animals entire; washed and then split lengthwise so that 

 food particles could be removed. Sections as well as the entire 

 alimentary canal were then tested with the various indicator 

 solutions. When the entire alimentary canal is left in the 

 indicator solution for a short time and then examined under a 

 binocular microscope with strong illumination the differences in 

 1 .11 values 'if the various parts are strikingly brought out. 

 Animal- starved for various periods of time, during which the 

 alimentary canal was completely emptied of food, gave pH 

 val nilar to those found for normal individuals. 



1 lie accompanying table shows the average as well as the ran^e 

 in pi I values for the blood and alimentary' canal of the species 

 mined. The average pH value for blood of yrasshopprrs 

 n- to be 6.8. The dark brown fluid usually emitted by the 

 animal when handled is quite acid in reaction. This fluid is 

 doubtless made up of regurgitated substances from the cn>p as 

 \\rll as salivary secretions. The crop is generally quite acid in 

 reaction while the blind pouches or caeca seem always to be less 

 acid than the crop. The stomach or that part of the alimentary 

 (anal into which the caeca open, varies to a considerable extent 

 in its reaction, being at times quite acid and at other times 

 neutral or alkaline. The middle and posterior end of the 

 stomach are usually less acid than the anterior end. The 

 intestine and rectum, that part of the alimentary canal posterior 

 to the point of entrance of the Malpighian tubules, also varies 

 considerably in its reaction. In some species a rather marked 

 alkaline condition is noted while in others both acid and alkaline 

 reactions are found. 



The pH of the blood of grasshoppers is of interest inasmuch as 

 it is approximately the same as that found by other authors for 

 diltcivnt insects, e.g., honey bee (Bishop 2), silkworm (Jameson 

 and Atkcn- 31. It would be of considerable interest to know if 

 insect blood functions in the transportation of gases, etc., as in 

 the > of mammalian blood. Some phases of this question 

 e been recently discussed by Bishop (2). Muttko\\>ki (6) in 

 studies on the respiration of insects has pointed out that the 

 blood reacts with the oxidation tests for haemoglobin regardless 

 ol the specii - (l f insect. These tests (guaiac, P-diamino-benzene, 

 a-naphthol ha\e been repeated on grasshoppers used in the 



