42 THE DISEASES OF DOMESTIC ANIMALS. 



Roell says the disease is attributed to hot and sultry weather, 

 uncleanly pens, and offering to the swine of spoiled, moldy food 

 and decomposing material in general. 



Harms seems to be the first to have discovered germs in the 

 blood, and to have attributed to them an etiological importance, as 

 he found the blood and other parts of diseased swine, as well as the 

 food, replete with these organisms. 



Bollinger also describes micrococci and short cylinder bacteria 

 in the blood, but does not consider the etiological connection with 

 the disease as established. 



Roell says further, " The disease has not yet been produced by 

 inoculation." 



Spinola wrote a monograph on the "Diseases of Swine," Berlin, 

 1842, and considers the disease to be of a gastro-bilious character ; 

 and says further, it is observed to occur in those swine which have 

 much rest, a surplus of strong feed, especially that which is of a 

 spirituous nature — brewers' grains, etc. — which incline to a surplus 

 production of gall and its accumulation in the system. He also 

 considers the above climatic conditions to exert an influence in the 

 generation of the disease. 



It remained, however, for American veterinarians, not indige- 

 nous to the country, to establish beyond doubt the true nature of 

 this disease. 



The results of the studies of Messrs. Law and Detmers show the 

 disease to be of an infectious and contagious nature, and capable of 

 transmission to other animals as well as swine by inoculation. 



They discovered in the blood peculiar elements having a globu- 

 lar or micrococcus form, as well as staff-like bodies — the mature 

 form — to which Detmers gave the name of 



Bacillus Suis. 



These objects are found invariably in the blood, urine, mucus, 

 exudations, etc., in all pathologically changed tissues and in the 

 excrements of the diseased animals, and constitute, beyond all ques- 

 tion, the etiological momenta of the disease. These bacilli undergo 

 several changes, and require a certain length of time to fulfill their 

 development ; consequently, if introduced into an animal organism, 

 some time must pass (the incubational or colonization period) before 

 the morbid phenomena become apparent. Three stages of develop- 

 ment may be observed — viz., the germ, or micrococcus stage ; the 

 bacillus, or rod-bacterial stage ; and the proliferating or germ-pro- 

 ducing stage. 



