340 CLINICAL BACTERIOLOGY. 



ear-vein of a rabbit, the animal will die after the lapse of 

 two or three days in consequence of a general mold-myco- 

 sis. In all of the organs, most abundantly in the kidneys 

 and in the liver, small, whitish-gray nodules are present, 

 which, when viewed microscopically, are found to consist 

 of a dense network of mycelial threads. These fungous 

 vegetations never, however, contain fruit-bearers or co- 

 nidia. Careful investigation has shown that germination of 

 the injected spores has taken place, but that fruit-formation 

 never takes place in the animal organism. 



By reason of its deficiency in free oxygen and its alkaline 

 reaction the organism does not constitute a suitable nutrient 

 medium for most molds. The overwhelming majority of 

 these die when introduced into the body, whether through 

 the breath or in any other way. The few varieties that 

 survive at all prove pathogenic only by germinating, and 

 acting as foreign bodies inducing disturbances mechanically 

 through irritation and vascular occlusion, etc. They do 

 not undergo fructification or actual multiplication. Noth- 

 ing likewise is known with regard to any chemic activity on 

 the part of molds or budding fungi in the body. In a 

 certain sense the mold-mycoses are, accordingly, not true 

 infectious diseases, as they are not attended with multipli- 

 cation of the exciting agent, and with intoxication. Suc- 

 cess in inoculations with pathogenic molds depends, there- 

 fore, also upon the number of spores injected. The number 

 of disease-foci corresponds exactly with the number of 

 spores introduced, and the animals die as a result of the 

 extent of the foci of disease alone. The pathogenic molds 

 are, besides, inherently pathogenic, and likewise the non- 

 pathogenic molds are always nonpathogenic. Augmenta- 

 tion or attenuation of pathogenicity can not be effected. 

 The pathogenic varieties are not equally pathogenic for all 

 animals. Thus, the mucor corymbifer, which destroys rab- 

 bits, is harmless in dogs. 



Pathogenic molds are quite widely distributed in nature. 

 It is only necessary, for instance, to expose unsterilized 

 bread-pap in a closed beaker for one or two days to a tem- 

 perature of from 30 C. (86 F.) to 40 C. (104 F.), in 

 order to see a dark-green fungous coating form, consisting 

 of aspergillus fumigatus. The culture is generally pure, as 

 at a temperature of between 30 C. (86 F.) and 40 C. 

 (104 F.) the aspergillus overgrows all other molds. If, 



