Toxins, Mixed Infection. 535 



and not alone toward bacilli of a new strain, hence in metastatic autoinfection. 

 The fact that metastatic tuberculous infection occasionally occurs in human beings 

 and animals with chronic tuberculosis (Joest) does not necessarily contradict this 

 statement. Eepeated or massive hematogenic infection from chronic foci may 

 establish a new focus of infection even in relatively immune tissues. 



Toxins. Tubercle bacilli owe their activity to endogenic 

 toxins as well as to toxic products of metabolism. Necrobiosis 

 and caseation in tlie tubercle is tlie result of the endogenic 

 toxins. Subcutaneous injection of dead bacilli results in a 

 local sterile abscess, necrosis, caseation and cachexia. Alkaline, 

 ether- and benzine-extracts of the bacilli will produce a similar 

 result (Koch, Weyl, Auclair & Barbier, Siegenbeck van 

 Heukelom). On the other hand the fever which occurs in the 

 course of the disease is caused by the products of metabolism 

 which later also are to be found in the filtrates of cultures 

 which, in a concentrated form, are known as tuberculin (Koch, 

 Behring). 



According to Marmorek the toxin that circulates in the blood of an infected 

 animal and with which the bacilli themselves are also impregnated is not the same 

 as that in tuberculin. This toxin is formed outside of the animal body m fresh 

 cultures growing in leucotoxic serum, e. g., liver bouillon. When subcutaneously 

 injected into horses it produces inflammatory edema. Doses of 5.0 cc. will kill 

 guinea pigs. According to Calmette & Bretton boiled cultures act similarly to 

 tuberculin. According to A^allee, Martin & Vaudremer bacilli which have had their 

 fat contents removed act similarly to hyperactive tuberculin. Cantacuzino observed 

 that the intravenous injection of large doses into guinea pigs rapidly produced 

 death following hypothermia, degeneration of the kidneys and the heart and increase 

 of eosinophiles in the blood. Small doses produce chronic disease. Maragliano 

 recognizes two toxins of the tubercle bacillus, an exogenous thermolabile toxalbumin 

 (destroyed by boiling), producing diaphoresis and hypertrophy and an endogenous 

 thermostable toxoproteid (heat resisting) said to have a hyperthermic action. 

 Koeppen on the other hand could not discover any difference between these two 

 groups. De Waele inserted collodion capsules filled with cultures of tubercle bacilli 

 under the skin of experiment animals. A few weeks later they reacted to tuberculin. 

 Moussu inserted clay tubes filled with cultures of bacilli under the skin of cattle 

 and produced the same result. 



Mixed Infection. Tuberculous organs constitute a favor- 

 able soil for the growth of saprophytes as well as for other 

 pathogenic bacteria. These are carried to open lesions by the 

 air 01^ the blood stream transports them to closed cheesy foci. 

 They may multiply in these places and are then liable to modify 

 the anatomical character of the lesions as well as the clinical 

 course of the disease. It is also possible that pathogenic 

 organisms produce certain primary lesions and thus prepare 

 the soil for an easier infection by the tubercle bacilli. The 

 pvogenic bacteria are particularly important in this respect, 

 a' purulent and soft character of tuberculous foci being fre- 

 quently, though not always, an indication of such a mixed 

 infection. Such a metamorphosis of a dry cheesy focus into 

 a soft purulent mass favors the dissemination of the tubercle 

 bacilli in the organism, if only because they are usually present 

 in them in large numbers (Bongert) and furthermore the fre- 

 quent development of tuberculosis following catarrhal affections 

 and acute pneumonia points to the favorable influence of other 



