j^i2 Journal of Agricultural Research voi. xxii. no. s 



sion for 2 hours at 37° C. followed by 48 hours in a refrigerator resulted 

 in partial hemolysis. Several controls in which the suspension of corpus- 

 cles alone and equal quantities of the suspension of corpuscles and extract 

 were employed showed complete absence of hemolysis. 



These experiments indicate that alcoholic specimens are much less 

 potent in their hemolytic action than fresh specimens. This is doubt- 

 less due to the loss of hemolytic substance to the alcohol. In confir- 

 mation of this view the writer found that dried hookworms from the 

 dog freed from their ether-soluble and alcohol-soluble fractions were 

 not hemolytic to washed erythrocytes of rabbits. The ether-soluble 

 fraction left rabbit corpuscles intact. The alcoholic extract was un- 

 fortunately lost before it was tested for its hemolytic potency. 



4. EFFECT OF NORMAL SERUM ON HOOKWORM HEMOLYSIN 



Experiment 16. — To each of four tubes containing 0.5 cc. of blood 

 corpuscles from the same lot as that used in experiment i there were 

 added 5 drops of fresh hookworm hemolysin described elsewhere in this 

 paper, and i, 2, 3, and 5 drops of dog serum, respectively. The tubes 

 were incubated for i hour at 37° C. No hemolysis was observed in any 

 of the tubes. After the tubes had remained in an ice box overnight it 

 was found that with the exception of the tube to which but i drop of 

 serum was added and which showed a faint trace of hemolysis, inhibition 

 of hemolysis was complete. 



Experiment 17. — Five drops of a 5 per cent suspension of washed 

 rabbit corpuscles from a lot which was susceptible to extract of alcoholic 

 specimens were only partially hemolyzed when 3 drops of normal rabbit 

 serum were added. It was also found that as a result of heating the 

 serum for 30 minutes at a temperature of 56° C. the antihemolytic prop- 

 erty was neither destroyed nor impaired. 



Experiment 18. — ^Washed rabbit corpuscles, which were completely 

 hemolyzed when equal parts of a 5 per cent suspension of cells and equal 

 parts of fresh salt-solution extract were mixed and incubated for 20 

 minutes at37° C, were found to resist a double quantity of the hemolysm 

 in the presence of various inactivated sera, as follows : In each of three 

 tubes there were placed 5 drops of the suspension of corpuscles, 10 drops 

 of the extract, and 2 drops of heated rabbit, horse, or dog serum (60° 

 to 65° for 30 minutes). The mixtures were incubated for 2 hours 

 without any resultant injury to the blood corpuscles. After having 

 been kept in a refrigerator for 18 hours after incubation, the tubes con- 

 taining dog and rabbit serum showed faint traces of hemolysis, while 

 the tube containing horse serum showed no hemolysis. 



Experiment 19. — To each of two tubes containing 3 drops of unwashed 

 rabbit blood there were added 7 drops of physiolo^cal salt solution. 

 These mixtures were incubated for 2 hours with 5 and 10 drops of fresh 

 ^tract, respectively, at 37" C. No hemolysis was produced. The 



