ON THE BACTERIA. 161 



connected with the presence and development of certain Bacteria ; 

 and where, as in the case of Anthrax and Chicken Cholera, these 

 organisms can be cultivated outside the animal body, and on being 

 inoculated in a healthy subject, are found to give rise to the malady, 

 there can be no doubt that they constitute the actual cause of the 

 disease. 



Besides these, it is probable that many other diseases, as cholera, 

 measles, scarlet-fever, typhoid, diphtheria, and others of a 

 zymotic character, are all caused by Schyzomycetous Fungi ; but 

 no complete or exhaustive observations are as yet published con- 

 cerning them. The analogy of their symptoms with those of the 

 known bacterial diseases affords a strong presumption in favour of 

 the theory. Their contagious nature is most naturally accounted 

 for on the supposition that the poison germs of the disease, when 

 passing from the body of the sufferer, impregnate the atmosphere 

 around him, so that anyone in that atmosphere must necessarily 

 breathe these germs, which enter through the delicate walls of the 

 capillaries of the air-cells into the circulation, where they live, grow, 

 and reproduce others like themselves. The premonitory stage of 

 incubation corresponds with the time taken by the development of 

 the Bacteria in the system after infection, the febrile state with 

 their full development, and the period of convalescence with the 

 gradual decline of the Bacteria^ when the nutritive elements on 

 which they exist are exhausted ; while the freedom from liability 

 to a subsequent attack also holds good with the analogies of 

 Anthrax and Chicken Cholera. 



One of the most important questions at the present time is, 

 What is the practical value of the organisms which seem to be so 

 intimately connected with the formation and growth of tubercle ? 

 Many well qualified observers are studying the subject, and we 

 may hope that ere long much important light will be thrown upon 

 it. The discovery, at all events, enables us to understand how 

 consumption may be contagious, though at present it does not 

 afford any additional proof that it is so, and on the other hand 

 it has rather increased the difficulty of explaining its hereditary 

 character. 



It may no doubt help us in determining whether a suspected 

 case is actually one of consumption or not ; as when looked for by 



