84 DETERMINATION OF SPECIES. 
5. Agar-tubes. 
6. Potato. 
7. Milk. 
8. Blood-serum. 
B. Biochemic features. 
1. Temperature relationship (activity of growth at 
18°-22° C. and at 36°-38° C. and thermal death-point). | 
2. Relation to free oxygen (aérobic and andérobic 
growth). 
3. Relation of growth to acidity and alkalinity of 
media. 
4. Action upon gelatin (presence or absence of lique- 
faction). 
5. Action upon proteids (milk and serum). 
6. Action upon carbohydrates (fermentation and gas 
formation). 
7. Action upon nitrates. 
8. Production of indol. , 
g. Production of acid or alkali. 
10. Pigment formation. 
11. Development of odor. 
C. Pathogenesis. 
The following tests are of value in certain cases : 
I. MORPHOLOGIC. 
1. Staining reactions with special stains. 
2. Study of flagella by special stains. 
3. Permanency of morphologic characters after long- 
continued growth and successive transplantation upon 
artificial media. 
4. Photographic reproductions of isolated bacteria. 
5. Cover-glass impressions. 
II. PHysIOoLoGic. 
A. Cultural characteristics, mode of growth in or upon— 
1. Litmus gelatin. 
2. Léffler’s blood-serum. 
3. Synthesized media. 
4. Photographic reproduction of characteristic cultures. 
