Variations in Resistance of Red Blood Cells. 165 



amboceptor, and likewise the titrations of the different cells against 

 immune serum gave the same relative results whether the amount 

 of immune serum was kept constant and the amount of complement 

 varied, or the amount of complement was kept constant and the 

 amount of immune serum varied. 



The serum of the three animals was also tested for its tonicity 

 by diluting with graded amounts of distilled water and adding to 

 2 c.c. of each dilution .1 c.c. of 30 per cent suspension of freshly 

 washed cells from sheep F. The serum of sheep T did show a very 

 slight lowering of its tonicity following the hemorrhage. The sera 

 obtained on three different days were tested simultaneously. 



table III. 



Hemolysis of Red Cells of Sheep F in Serum of T Diluted with Distilled 



Water. 



Per Cent, of Serum. 



5° 



525 



55 



57.5 



60 





+ + 



+ 



+ 







Serum of T, April 23 



+ + + 



+ + 



+ 



+ 





Serum of T, April 24 



+ + + 



+ + 



+ 



+ 





( + + + + = complete hemolysis.) 



The tonicities of the sera of the three animals were very nearly 

 the same and had no relation to the rather wide variations in the 

 resistance of their red cells. 



Smith and Brown working with horses' blood found marked 

 variations from the average resistance to salt solutions of low 

 tonicity. About 10 per cent of horses have red cells very sensitive 

 to hypotonic solutions. The sera of these horses were rather 

 constant in tonicity. Cornwall 1 found that the apparent tonicity 

 of sheep serum has no relation to the mean lytic point of the red 

 blood corpuscles of the individual and is largely due to lipoids. He 

 also found marked variations in individual animals. 



Experiments of different workers on the effect of hemorrhage 

 on the resistance of blood cells have given varying results. Smith 

 and Brown 2 working with horses found a slight decrease in the 

 resistance to hypotonic salt solution only after many large hemor- 

 rhages and only in some individuals. Itami and Pratt 3 also work- 

 ing with rabbits, found a slight increase in resistance. 



1 Cornwall, Jour, of Hygiene, Oct., 1912, Vol. 12, p. 245. 



2 Smith and Brown, Jour. Med. Res., 1906, Vol. 15, p. 415. 



3 Itami and Pratt, Biochem. Zeit., 1909, Vol. 18, p. 302. 



