SPORES HABITS. 73 



If Dr. Koch has traced the life history of the bacillus 

 tuberculosis aright, it multiplies only by the formation of 

 spores, never by fission or budding, and the spores are formed 

 under the conditions of the activity of the organism. Only 

 this one instance of this exclusive multiplication by spores is 

 recorded, however, in the whole field of research among these 

 forms of life. Many, however, have been found to form 

 their spores during the continuance of the conditions of their 

 activity, as the bacillus septicus, micrococci of gangrene, and 

 some others. 



These facts have a very important bearing upon the modes 

 of communication of contagious and infectious diseases, and 

 may finally serve to explain some of their peculiarities. For 

 instance, if it is found that a disease-producing organism pro- 

 duces spores only when there is a lack of moisture, or at a 

 temperature below that of the human blood, it will be clear 

 that the spores will be produced only after elimination of the 

 organisms. If, in connection with this fact, it is found that 

 the developed organism is destroyed by drying, which is 

 inferred, then it becomes clear that infection will not be likely 

 to take place, through the medium of the air, directly from 

 the sick to the well. Drying of the eliminated organisms 

 must first occur, during which the spores are formed, 'and then 

 the drying must be continued until the particles are ready to 

 be wafted about by the air currents and in this manner be 

 carried to the well persons. Dr. E. D. Salmon (Medical 

 Record for April, 1883) has developed the idea that the intro- 

 duction of the spores of the bacillus anthracis produces a 

 different result from the inoculation with the developed organ- 

 ism, under certain conditions. 



If this bacillus be cultivated continuously under conditions 

 which will not allow of spore formation, it will be weakened 

 in virulence, so that its introduction will cause a mild type of 



