STUDY OF FORM AND GROUPING. 89 
B. Biochemie. 
1. Minimum, optimum, and maximum temperatures 
of growth. 
2. Growth in atmospheres of various inert gases (when 
anaérobic power of growth has been determined). 
3. Optimum reaction of media and reaction limits, acid 
and alkaline (indicated by phenolphthalein). 
4. Chemic properties and solubility of pigments pro- 
duced, and spectroscopic observations upon the pigment. 
C. Pathogenesis. 
1. Inoculation of various species of animals, with 
minute study of the pathologic changes produced. 
2. Immunity-producing properties. 
3. Agglutinating properties of specific sera. 
4. Determination and isolation of toxic substances 
(from non-pathogenic, as well as from pathogenic, bacteria). 
A suitable blank should be prepared, on which 
are recorded the observations made on each species. 
The appended form (pages 86, 87) is substantially 
the one recommended by the Bacteriologic Com- 
mittee of the American Public Health Associa- 
tion. 
A further explanation in regard to some of these 
points is required. 
(a) Study of Form and Grouping.—Determine 
and describe the morphology from the growth 
obtained upon at least one solid medium and in at 
least one liquid medium. Growth at 36°-38° C. 
should in general be not older than from twenty- 
four to forty-eight hours, while growth at room- 
temperature (18°-22° C.) should be not older than 
from forty-eight to seventy-two hours. Growth on 
solid media may be studied from cover-glass prep- 
arations ; in liquid media growth is best observed 
