9 6 



Scientific Proceedings (73). 



Our own experiments, which were undertaken as a part of the 

 extensive studies of the New York State Commission on Ventila- 

 tion, have dealt with this same problem of the effect of moderately 

 high temperatures and were carried out in the bacteriological 

 laboratores of the University and Bellevue Hospital Medical 

 College. 



Normal healthy rabbits were kept (2-4 at a time) in an incu- 

 bator, 25"x48"x 12', at a temperature ranging from 29°-32° C. 

 Control animals were kept at room temperature (i8°-2i°). At 

 the beginning of the experiment each rabbit was bled (1 to 2 c.c.) 

 and then inoculated intravenously with x /i c.c. of a 50 per cent, 

 suspension of washed sheep erythrocytes. During the experi- 

 mental period each rabbit was bled once a week for trial titrations 

 of the hemolytic activity of the serum, and inoculations with the 

 sheep cells in increasing doses were made twice a week during 

 this period. 



The hemolytic activity of the serum was determined as follows: 

 The rabbit serum was inactivated at 55 0 C. for one half hour. 

 A 5 per cent, suspension of sheep corpuscles was used, and for 

 complement, normal guinea pig serum diluted 1-10. 



The rabbit serum was prepared in varying dilutions, as indicated 

 by the results of the previous titrations, and each dilution was then 

 titrated in the same way. 



A series of ten test tubes was set up with 0.1 c.c. of sheep 

 corpuscle suspension and 0.1 c.c. of diluted guinea pig complement, 

 and varying amounts of rabbit serum. The test tubes were then 

 placed in a water bath at 37 0 for 1 hour. At the end of that time 

 readings were made, and the smallest amount of rabbit serum of 

 the dilution which gave complete hemolysis was taken as the 

 hemolytic unit. Thus, if .06 c.c. of a dilution of 1-500 was the 

 smallest amount of serum giving complete hemolysis, then .06 of 

 this solution was taken as the hemolytic unit (.06x1/500 = 

 1/8333 c.c. = .120 cubic millimeters) and this decimal, representing 

 the actual dilution of serum in cubic millimeters found effective 

 under the conditions of the experiment, was taken as the measure 

 of the hemolytic power of the serum. The figures in the table 

 (used as ordinates in the chart) are derived in this way. 10 in 

 the table means that 1/100 of a c.c. of serum (10 cubic mm.) 

 showed no hemolytic activity. The error introduced into the 



