102 THE DISEASES OF DOMESTIC ANIMALS. 



In considering the question of disinfection we must ever bear in 

 mind that the fission-fungi, or their spores, always occnr in one of 

 two conditions ; that is, moist or dry. This fact should always be 

 settled before we decide as to our disinfecting procedures. When 

 in a moist medium, bacteria are much more easily destroyed than 

 when united with a dry. 



If we meet with them in a fluid, a boiling-heat is necessary to 

 their destruction. Temperatures of 77° to 10^° Fahr. are in general 

 favorable to bacterial life. The most advantageous has been found 

 to be 95° Fahr. The resistibility to high temperatures varies in the 

 different bacteria. A temperatui-e of 113" to 122° Fahr. has been 

 found sufficient to kill bacteria thernio, while bacilli have been 

 found to resist 176° Fahr. Extreme degrees of cold are far less 

 effective to their destruction than heat. We have too often assumed 

 that when our antiparasitics, or, better, antiseptics, have prevented 

 the fermentative processes, the germs have been destroyed also. 

 "While heat is the most effective of all the disinfectants, we shall 

 make no mistake in adding to it those chemicals which are at enmity 

 with bacterial life. 



Nageli sums up his remarks on disinfection as follows : 



1. The infectious elements can not be securely destroyed when 

 in an absolutely dry condition. 



2. Boiling-heat can only surely kill them when they are in a 

 moist or fluid medium. 



3. The antiseptics which have gained acceptance are not posi- 

 tively death to them ; they only place them in an inactive condi- 

 tion, that is, consume them. (This argument is open to the objec- 

 tion that, in disinfection, the disinfectants have been, or have to be, 

 used in too diluted a condition, or in such a way as not to come 

 either directly or in sufficient volume in contact with the bacteria. 

 This last must nearly always be the case in spray or smoke disinfec- 

 tion, which we believe to be an illusion.) 



4. They are changed, not destroyed, by decomposition of media, 

 by means of a surplus of water or heat, so that they lose their infec- 

 tious properties. 



5. They are harmless when removed in a moist condition. 



The true value of the internal application of the antiseptics is of 

 a very questionable nature ; for these materials exert fully as poi- 

 sonous an influence upon the autositic as the parasitic organism. 



In some cases, as in intermittent fever, it would seem as if we 

 could bring the organism so under the influence of quinine as to act 

 against the proliferation of the spirillum. That this bacterium dis- 



