32 DISEASES OF SWINE AND OTHEE ANIMALS. 



chord ulcerated, and an abscess tlie size of a hen's Qg'^ in liglit side of 

 scrotum. Internally all lymphatic and mesenteric glands enlarged; 

 anterior portion of both lungs CA'crywhere, Avith their Avhole external 

 surface, and x)Osterior portion at some places adhering (coalesced) to the 

 costal pleuia ; luimerous smaller and larger embolic tubercles, pieseut- 

 iug the appearance of incipient abscesses, in anterior portion of both 

 lobes of the lungs, but more numerous and more develo])ed in right lobe 

 than in the left ; remainder — posteiior parts of both lobes — gorged with 

 exudation ; snmll quantity of straw-colored serum in the chest and in 

 the pericardium. In abdominal cavity, liver rather hard (sclerotic), its 

 connective tissue apparently hyi)ertrophied. One small tape-worm, not 

 over one and a half inches long, in jejunum, and numerous small, inci])- 

 ient morbid growths or ocher-colored decaying nodules in ciccum. (See 

 photograph, Plate III.) No other morbid changes. 



Besides these numerous morbid changes, which must be looked upon 

 as x)i'oducts of the morbid i>rocess of swine-plague, some species of en- 

 tozoa, a few of which have abeady been mentioned, have occasionally 

 been met Avith ; but as their presence is merely accidental, that is, has 

 nothing whatever to do with the disease in question, a brief mention of 

 this occurrence will be sufficient. Strongilus paradoxus has been found 

 in small numbers in the bronchial tubes of a f(iw pigs in one herd only — 

 Mr. Bassett's. TricJiocephalus crenatns (whip-worm) has been found in 

 small numbers in the blind end of the cwcum of four animals, belonging 

 to two different herds. A small tape- worm was once found in the 

 jejunum, as has been stated, and a few other entozoa (nematoids) Avere 

 found in four or five instances in the choledochus, gall-bladder, and 

 hepatic ducts (in one case as many as twelve worms), and twice in other 

 intestines. 



What I have so far related was comparatively easilj^ ascertained. Nu- 

 merous examinations of tliseased animals, frequent visits to affected herds, 

 and Hfty -three post-mortem examinations revealed the facts, and all that 

 was necessary was to observe and take notes. But the principal object 

 of the investigation was to devise means to i^revent the immense losses 

 caused every year by that most fatal disease, swine-plague. (I have 

 adopted that name, because the disease, if anything, is a real plague ; 

 and the name is sufficiently comprehensive to cover the whole morbid 

 I)rocess, and so simple that I have no doubt it will soon supercede, exen 

 among farmers, that very improi)er name of hog cholera.) 



To dcAise such means, a more reliable basis than a mere knowledge 

 of the various features of the disease had to be gained. The real nature 

 of the morbid process, and the true cause or causes, had to be ascertained. 

 Above all, it had to be decided as to whether swine-plague is a con- 

 tagious disease or not; and if contagious, the means by which the 

 contagion is conveyed from one place and irom one animal to another; 

 the manner in which it enters the animal organism, and, if possible, 

 the nature of the same. This could not be done by simply visiting 

 diseased herds and examining sick and dead animals ; it was necessary 

 to make experiments and to observe and to record the results. This 

 I have done, and before I proceed any further it may be best to give, 

 first, a condensed account of the experiments which I have made for 

 the i^urpose of settling those points, so as to give others an opportu- 

 nity to form an o])inion as to the correctness of the conclusions I have 

 arrived at. I will mention again, that in making those experiments, 

 in noting the results, and in making the necessary and very numerous 

 microsco])ical examinations, I Ikiac been ably assisted by my friends, 

 Dr. l'\ W. Prentice and Prof. T. J. Burrill, of the Illinois Industrial 

 UniA'crsity. 1 commenced those experiments alter 1 had gained con- 



