CONTAGIOUS DISEASES OF DOMESTICATED ANIMALS. 371 



of swine plague caunot be tiie work of worms or entozoa. I will not 

 dcDy that the latter, if i)reseut in large uuaiberw, or occurring in weak, 

 starving, and neglected animals, may bo able to cause considerable mis- 

 chief, and even death ; but such cases must not be mistaken for swine 

 plague. Worms or entozoa are found very often in healthy hogs and 

 pigs independent of the morbid process of swine plague, and have no 

 connection whatever with that disease. I therefore simply mentioned 

 their occurrence iu my first report, and did not deem it necessary to 

 dwell on their natural history or on the damage which they may be able 

 to do. 



The most essential difference between the morbid features presented 

 at the post mortem examinations i^revious to December 1 and those 

 found in the animals examined in the winter and spring, consists in a 

 more frequent affection of the large intestines (ctecum and colon) in the 

 summer and fall, while in the winter and spring the principal seat of the 

 morbid process was almost im'ariably in the orgaiis of the chest, but 

 especially iu the })ulmonal tissue. In the summer and fall, or previous 

 to December 1, ulcerous tumors in either one or both of the large intes- 

 tines, cfecum and colon, were found in about 90 per cent, of the whole 

 number of cases examined, while iu the winter and spring they did not 

 exist in more than about 50 per cent. 



This diiibrence it seems to me is not accidental, but admits of an ex- 

 planation. At any rate, the predominating affection of the organs of 

 the chest, and especially the extensive embolism and exudation iu the 

 lungs, observed invariably in every case in which the large intestines 

 were free from ulcerous tumors, may be traced to distinct causes, acting 

 principally during the winter. Swine, especially in the cold season of 

 the year, on entering their lair and going to sleep in the evening, are in 

 the habit of crowding close together, of lying on top of each other, and 

 of frequently passing the night in very close quarters. Such crowding 

 into a narrow space cannot fail to heat their bodies, to vitiate the at- 

 mosi)here, and to accelerate the respiration. Consequently it will pre- 

 vent a proper decarbonization of the blood and retard its circulation in 

 the i^uliiional capillaries, and cause more or less congestion of the lungs, 

 and prepare those organs for just such, morbid changes as are effected by 

 the bacilli and their germs. In the morning, after the animals have been 

 heated during the night, and are rising ti'om their lair iu search of food, 

 the air, especially in the winter, is usually cold and chilly, and, but a mo- 

 ment ago reeking and steaming with perspiration, they become chilled 

 and commence to shiver. Such a sudden change of tenjj^ei^aturo neces- 

 sarily causes a disturbance of the functions of the lungs and of the skin, 

 contracts the expanded capillary vessels of the latter, and thereby com- 

 pels the blood to rush to the heart and to the interior parts of the body. 

 All this cannot fail to prcdisjiose, especially the lungs and heart, to be- 

 come the x)rincii)al seat of the morbid process of swine plague, if the in- 

 fectious principle^ the hacilli and their germs, have entered the organ- 

 ism, jiloreover, it ai)pears to be probable that an imperfect decarboni- 

 zation of the blood promotes the tendency of the bacillus-germs and 

 partially developed bacilli to agglutinate to each other, and to form 

 those irregularly shaped clusters which clog the capillaries, and cause 

 in that way extravasation of blood and extensive exudations. Some 

 other influences may be acting, but tliose mentioned seem to be the 

 principal ones. The greater frequency of morbid changes in the large 

 intestines nnd iu the digestive canal in general, in the summer and fall, 

 has probably an equally good cause. 



Swiijc as a rule lead a more indei)endent life in the summer and fall 



