XXI] PATHOGENIC ORCxANISMS 553 



degenerate and die off; the diphtheria bacilli of a gelatine 

 culture injected into the subcutaneous tissue of a guinea-pig 

 • — one-fifth of a culture per one kilo animal weight — produce 

 typical tumour and death in thirty to thirty-six hours ; when 

 from the same stock one-third or one-fourth of the culture 

 per 300 — 400 grms. guinea-pig is injected into the peritoneal 

 cavity, nothing happens, the bacilli very soon degenerate 

 and are killed. 



When hay bacillus, staphylococcus taken from septic 

 fluids, bacillus mesentericus, bacillus coli, or other sapro" 

 phytes are injected into the vascular system of a healthy 

 animal, no disease follows, the microbes soon disappear ; but 

 if in such an animal a focus of inflammation, necrosis, or 

 ulceration has been previously established this focus becomes 

 easily the soil for the growth and multiplication of those 

 saprophytes (Wyssokovitch, Zeitschr.f. Hygiefie, i.). Of the 

 same nature are the observations constantly to be made 

 of micrococci of various kinds, pneumococcus, and of 

 bacillus coli or proteus vulgaris being found present, as a 

 secondary invasion, in inflamed portions of various organs — 

 liver, lung, spleen, kidney — in which the inflammation had 

 been caused by some other antecedent disease. 



Even in the case of an animal highly susceptible to a 

 particular specific microbe it will be noticed that not all 

 tissues of such animal are favourable for the life and growth 

 of the microbe. While in the so-called blood diseases : 

 septicsemias of different kinds, anthrax, fowl cholera, &c., the 

 microbe lives and thrives well in the blood and blood-vessels 

 of all tissues, this is not the case in many other instances, e.g. 

 diphtheria, tetanus; cholera, tubercle, typhoid fever, and others. 

 {b) A normal frog is insusceptible to anthrax infection, 

 but if it be kept heated to the temperature of a warm- 

 blooded animal it is susceptible (Petruschki). A normal 



