70 DISEASES OF SWINE AND OTHER ANIMALS. 



tliat the blood, tlie cliaunel througli wliicli these must be carried to the 

 various organs in wliich they are found, must prove virulent. One of 

 Dr. Klein's ex]>eriments appears to neg'ative this conclusion, whereas 

 three of mine go to support it. From v^lvdi we know of the generation 

 of microphytes, it seems not improbable that at certain stages of its de- 

 velopment tliis specimen may fail to be injurious, or more probably the 

 germs may be filtered froin the blood, being arrested in the capillaries, 

 where they determine the morbid changes, a]'d thus many specimens of 

 blood may bo obtained which are destitute of the morbid element, initil 

 tliat is again produced iji abunda^nce by proliferation in the tissues. By 

 reference to my experiments, it will be seen that the blood ^vith which 

 the successful inoculations were made was taken from pigs in the last 

 stage of the disease, or just after death. Tliat the blood is virulent at 

 certain stages is unquestionable, and in the nature of things this can 

 scarcely fail to be the case, even if we were to set aside expeiiments and 

 reach our decision from the lesions alone. 



CAUSES. 



It has been no part of my x)iu-]iose to investigate the causes of this 

 disease apart trom the one specific cause of contagion. It was indeed 

 impossible to pursue Buch a line of inquiry at a distance from any dis- 

 trict where hogs are largely raised, where ihe disease prevails exten- 

 sively, and where, presumably, new generations of the poison are taking 

 place. One instance, however, of probable generation de novo has been 

 brought under my notice, and the attendant circumstances were such 

 that I think it important to x>ubhsli the prhicipal facts. In the end of 

 April, 1871, Colonel Hoffmann, of Horseheads, i'>urchased a large herd 

 of swine to consume the buttermilk of his creamery. The swme were 

 supplied Avith sheds, the open range of an orchard, witli i)lenty of shade 

 under the trees, on a gravelly soil, rismg al^ruptly 10 to 3 5 feet above 

 the general level of the valley, and were fed fresh buttermilk and corn 

 meal. All went well until late in June or early in July, when the hogs 

 began to sicken and died in large numbers, with the general symptoms of 

 the hog feve]\ I have ntentioned this mainly to negative the widespread 

 belief that the source of the troiible is in the exclusive feeding upon 

 com. Here we had a laxative and otherwise model diet, supplemented 

 only to a slight extent by corn. It may be well to state that in other 

 years, when he has purchased Western hogs, the disease has always 

 appeared within ten days or a fortnight after their aft-ival. When Kew 

 York State hogs only have been bought the jiestilence has not broken 

 out. 



In view of the strong assertions that pigs will not contract the disease 

 when fed in part on green food or on succulent vegetables — turnips, 

 beets, potatoes, apples, &c. — I had some subjects of exiieriment freely 

 supx>lied vv'ith potatoes and apples, but whenever the ]ioison was intro- 

 duced by inoculation I could detect no difference in the period of incu- 

 bation or the severity of the attack. 



It may be added that all uuArholesome conditions of feeding and man- 

 agement will fiivor the development of this as of other specific fevers, 

 by deranging the nutrition, disturbing the balance of waste and re- 

 l^air, loading (he blood and tissues with effete and abnormal products, 

 raising the body tem])eratnre, and on the whole bringing about a state 

 of the system (>xtn'm<>ly laAorable to the propagation and growth of 

 disease gerr.is. r.ut while the importance of all these maybe recog- 



