HYDROGEN ION CONCENTRATION IN BLOOD OF INSECTS. 367 



from the outside and comparisons made with those reared entirely 

 under laboratory conditions. 



Temperature during the course of the experiments ranged from 

 22 to 24 C. 



TABLE 5. 



Temp. 24. C. June 15, 1926. 



Samples E.M.F. Average pH. 



Buffer (5.65) (a) -57573 5-6i 



(b) -57580 



(c) .57560 



Romalea adult (a) .65250 6.90 



(b) -65555 

 Buffer (5.65) (a) .58210 5.69 



(b) .58088 



(c) .58006 



Romalea adult (a) .64553 6.79 



(b) .64553 

 Buffer (5.65) (a) .58173 5.67 



(b) -57953 

 Romalea adult (a) .65203 6.90 



(b) .65273 

 Buffer (5.65) (a) .58265 5.67 



(b) .57963 



(c) .57963 



Romalea adult (a) .65226 6.89 



(b) .65163 



Buffer (5.65) (a) .58200 5.67 



(b) .57742 



Explanation of Table 5. 



Part of daily record for June 15, 1926, to show method of procedure in making 

 determinations of blood pH values. Note that standard or buffer solution is 

 always read before and after every reading on blood as check on electrode. 



The results of the determinations are summarized in Tables 

 1-5. From an examination of these it is evident that considerable 

 variation exists in the hydrogen ion concentration of the blood of 

 the same and different species. No marked species, sex or age 

 differences have been detected. The variations shown can 

 hardly be due primarily to differences in food conditions since the 

 laboratory animals were all fed the same food, lettuce, and the 

 out-of-door animals had varied diets depending on the locality 

 from which they were taken. The data in the tables are summa- 

 rized and do not show individual variations which are to a degree 



