14 PATHOLOGICAL MYCOLOGY. 



for a considerable period, giving rise to marked histological changes 

 before the whole organism is appreciably affected ; whilst, on the other 

 side, the ferment is formed rapidly by organisms which grow rapidly, 

 and once formed, this ferment has an extremely toxic action — an 

 action which makes itself manifest at a very early period throughout 

 the whole of the organism attacked. 



Between the two extremes are such conditions as pyaemia, where 

 there are not only local manifestations in the tissues after death, but 

 also the acute toxic symptoms during life, in which case, too, the disease 

 runs an intermediate course as regards its rapidity. As pointed out 

 by Koch, these effects depend upon two elements— yzV-sV, the rapidity 

 of growth of the micro-organism which is attacking ; second, the rate 

 of secretion, and the quantity of the toxic element required to have 

 (.7) a local and (b) a general effect. The rate of growth of the different 

 micro-organisms may be readily observed in artificial cultivation 

 media, where, under favourable conditions, it will be found to corre- 

 spond very closely with the rapidity of occurrence of the local mani- 

 festations in the animal tissues. Anthrax kills very rapidly, and the 

 bacilli grow very rapidly in artificial media at the temperature of the 

 body ; whilst tubercle affects locally and gradually, and its organism 

 grows extremely slowly, and only under specially favourable con- 

 ditions. In twenty-four hours there is a large crop of anthrax 

 organisms, whilst there is usually no evidence of the growth of such 

 a brood of tubercle bacilli until about a fortnight has elapsed. 



12. These facts have a most important bearing upon the nature of 

 the processes which are met with in the various forms of disease in- 

 duced by micro-organisms ; and it would be almost possible to draw 

 two lines running parallel to one another, one of which might represent 

 the tubercle bacillus, the other the organism met with in septicaemia, 

 the one acting slowly and locally, the other more rapidly and generally. 



Neither organism can develop either its kind or its products if 

 deposited alone on a healthy surface. If, however, sufficient pabulum 

 is carried along with either of these organisms to supply it with nutri- 

 ment, then the products may be developed in sufficient quantities to 

 devitalise neighbouring tissues, or to neutralise that activity of the 

 cells which prevents their breaking down on the attack of the micro- 



