196 



Scientific Proceedings (76). 



kept (2-4 at a time) in a large incubator (12' x 2' x 4') at a tem- 

 perature ranging between 29 0 and 32 0 C. A similar series of 13 

 control animals was kept at room temperature (i8°-2i°). The 

 animals were immunized by giving them intraperitoneally suc- 

 cessively increasing doses of a suspension of killed typhoid bacilli. 

 The injections were given twice a week. Bleedings were taken 

 at weekly intervals and serum was drawn off from the clot and 

 diluted with sterile salt solution. 



For microscopic agglutination tests, one loopful of diluted 

 serum and one loopful of a twenty-four hour broth culture of the 

 typhoid bacillus were mixed on a cover glass, and a hanging-drop 

 mount made. This was incubated at 37 0 Centigrade and readings 

 made after one hour. In every case the figures in the table 

 represent the actual dilution of serum found effective; the larger 

 the fraction, the weaker the agglutinating power. 



The results of the experiments are given in full in Table I and 

 the averages by series in Table II. No general average can be 

 fairly calculated because the agglutinating power of all the rabbits 

 in Series V was so low that in a general average these Series V 

 figures swamp all the rest and the net result depends simply on 

 the number of Series V results included in a given week. 



table 1. 



Effective Dilution of Serum Expressed in Decimals. 







Heated Animals. 





Control Animals. 



eries 





Week. 



XI 



-n 

 a 



Week. 



(/J 



« 



1 



2 



3 



4 



5 





I 



2 



3 



4 



5 



I... 





.00500 

 .02000 



.00066 

 .00100 









101 

 102 



.02000 

 .00100 



.00025 

 .00067 









3 

















4 















II. . 



5 



.00200 

 .00050 

 .00200 

 .00200 

 .00500 



died 



.00050 

 .00010 

 .00010 

 .00010 







is 

 16 



17 

 18 



.00050 



.00020 



.00050 

 .00050 



.00012 

 .00012 

 .00010 

 .00012 



.00003 



.00010 

 .00010 

 .00010 



.00005 

 died 



.00010 

 .00010 







9 

 6 



.00100 

 .00012 

 .00012 



.00010 

 .00010 

 .00010 



died 



.00012 

 .00012 







7 

 8 







Ill . 



172 

 173 



.01000 

 .02000 



.00025 

 .00025 



.00020 



.00029 



.00020 



.00033 



.00050 

 .00050 



170 



171 



.01000 

 .01000 



.00010 



.00017 



.00013 



.00020 



.00017 

 .00025 



.00025 

 .00045 



IV . 



76 

 176 



.00018 

 .00050 



.00017 

 .00017 



.00017 

 .00017 



.00010 

 .00011 





93 



141 



.00500 

 .00500 



.00029 



.01000 



.00200 



.05000 



.00008 

 died 



.00010 











V . . 



92 

 143 

 I4S 



.10000 



.01000 

 .02000 



.01000 



.02000 

 .01000 

 .02000 





44 

 54 



72 



.10000 



.02000 

 .01000 

 .01000 



.01000 

 .01000 

 .01000 



.01000 

 .02000 



.00400 





.02000 

 .02000 



.02000 







.02000 















