DISEASES OF SWINE AND OTJIER ANIMALS. 45 



connective tissue is usually very abundant, especially in the frequently 

 pedicle-sliaped loot or basis. The proliferous morbid growths which 

 occur in the small intestines are almost destitute of it. If these morbid 

 growths or tumors are examined under the microscope, immense num- 

 bers of hacllli sins, some of them moving very rapidly and others at rest 

 (sometunes some other bacteria), and comparatively few bacillus-germs 

 will be seen. (See drawing III, iig. o; drawing VI, fig. 1; drawing V, 

 fig. 2; drawing IV, fig. 2; drawing VII, tig. 2, and drawing X, fig. 2.) 

 It appears to be probable that the excessive proliferous growth of the 

 ei)ithelium-cells and connective-tissue corpuscles is caused by a constant 

 irritation of the mucous membrane, or of the mcmhrana intermedia 

 (basement or Limitary membrane, Fleming) , produced by the hacilli. This 

 is the more probable, as those morbid growths occur especially in such 

 I)arts of the alimentary canal in M'hicli the food is known to tarry the 

 longest, in the csecum and in the colon. The luorbid changes (ulcera- 

 tions) found occasionally in the skin, where they sometimes cause whole 

 l^ortions to become mortified or decayed and to slough off, occur, it seems, 

 only in parts where a wound or lesion has been existing into which the 

 infectious principle, the bacilU or their germs, have been introduced ; so, 

 for instance, in the teats of brood-sows wounded by pigs, and in the nose 

 of hogs and pigs that have been ringed. These morbid changes in the 

 skin, it would seem, are produced in a similar way as the morbid growths 

 in the intestines, with only this difference, that instead of an excrescence 

 loss of substance makes its appearance. The skin is constantly exposed 

 to the atmospheric au*, and to a much lower and more changeable tem- 

 l)eratui'e than the mucous membrane of the intestines, and in consequence 

 the process of decay may become more rapid and may exceed the prob- 

 ably slower process of production. 



7. PERIOD OF INCUBATION. 



The period of incubation — perhaps more correctly "stage of coloniza- 

 tion," Klebs — or the time passing between an infection and the first out- 

 break of the disease, I have found to be from five to fii^een days, or on 

 an average of about seven days. Still, I have no doubt that in single 

 cases an outbreak may take place a day or two sooner, and in others, 

 though rarely, a day or two later. 



8. MEASUKES OF PREVENTION. 



As smnc-plague is a contagious or infectious disease, which spreads 

 everywhere by means of direct and indirect infection, and as a sponta- 

 neous develo])meut is problematic, or has not yet been proven, the prin- 

 cipal means of prevention must consist in preventing a dissemination of 

 the contagious or infectious principle, and in an immediate, promi^t, and 

 thorough destruction of tlie same Avherever it may be found. To i^revcnt 

 successfully a dissemination of the contagion and to secure a jn'ompt 

 destruction of the same, stringent legislation will be found necessary. 

 As it is, the contagion or the infectious priuci])le is, and has been, 

 disseminated through tlie wliole country in a wliolesale manner, as I 

 sliall sliow iiumedlatcly. During tlie first mouth of my presence in 

 Cluimpaign I stopped at tlu^. Doane House, a hotel belonging to the 

 Illinois Central Kailroad Company, and constituting also the railroad 

 depot. Every night car-loads of diseased hogs destined for Chicago 

 passed my window. Only a very short time ago, on one of the last 



