INDEX OF SUBJECTS 



1173 



Hydrocyanic acid gas, destruction of 



rodents by fumigation with, 109 

 Hydrogen in the nutrition of bacteria, 



31 



Hydrogen ion determination, 138-142 

 by colorimetric method, 138-142 

 Ph, meaning of, 138, 138 

 preparation of color standards for, 



141 

 indicators for various ranges of 



Ph, 140, 141 

 actual steps in, 142 

 ' ' buffer, ; ' definition of, 138 

 comparator, for reading, 142 

 Hydrogen sulphide produced by bac- 

 teria, determination of, 197 

 Hydrophobia, 900. See also Eabies 

 Hypersusceptibility, definition of, 352 



Doerr's classification, 352, 353 

 Hypomycetes, 983 

 in relationship to other plants, 40 



IMMUNITY, defined, 240, 241 

 natural, 241 

 racial, 242 

 species, 241 

 acquired, 243 

 active, 244 



produced with attenuated cul- 

 tures, 245 

 produced with sublethal doses, 



246 



produced with dead bacteria, 246 

 produced with bacterial products, 



247 



passive, 247, 248 

 antitoxic sera, 247 

 antibacterial sera, 247 

 Impetigo contagiosum, 392 

 Ictero-haemorrhagic fever, 885. See also 



Weil's disease. 

 Incubators, 190 



thermo regulators, 191 

 Indicators, theory of, 146 



for hydrogen ion determination, 140, 



141 



phenol red or phenolsulphonephtha- 

 lein, 141 



Indicators for hydrogen ion determina- 

 tion, brom-thymol blue, 141 

 cresol red, 141 



forjaddition to culture media, 147 

 Andrade, 147 

 china blue, 148 

 litmus, 147 

 neutral red, 148 



Indol production by bacteria, 199 

 method of testing for, 199 



Vanillin test, 199 



Infantile paralysis, 912. See also Polio- 

 myelitis 



Infantile splenomegaly, 1095 

 Infection, definition of, 230 

 factors determining, 232, 233 

 path of, 232 

 Infectious diseases, transmission of by 



direct contact, 380 

 by insects, 380 

 in intestinal group, 379 

 through respiratory channels, 378 

 Influenza bacillus, 482-501 

 biology of, 498 

 clinical picture, 482, 483 

 cultivation of, 495-498 

 preservation of, 497 

 epidemiology, 488 



characteristics of the epidemics, 



489 

 history of the last War epidemics, 



493, 494 



secondary and tertiary waves, char- 

 acteristics of, 492 

 transmission, 490 

 etiology of, 484 



arguments for and against Influ- 

 enza bacillus, 485, 486 

 filtrable virus theory, 486-488 

 in trachoma, 500, 501 

 isolation of, 495 



Avery sodium oleate agar, 496 

 morphology, 494 



occurrence of in inter-epidemic per- 

 iods, 499 



pathogenicity for animals, 501 

 stains, 494 

 toxin formation, 499 



