1 882.] A Pathogenic Schizopliyte of the Hog. 



and the cai 



10. Swine-plague has a well-marked period of incubation, or as 

 it has more appropriately been called stage of colonization, last- 

 ing from two to fifteen days, during which no morbid symptoms, 

 with the exception, perhaps, of a somewhat higher temperature, 

 can be observed. The average time which elapses after an inocu- 

 lation or infection has taken place till plain symptoms of disease 

 make their appearance, or till the morbid process has sufficiently 

 advanced to produce external symptoms, or a visible disturbance 

 of health, may be set down as from five to six days. All this is 

 easily explained if Schizophytcs constitute the cause, because 

 those introduced from without are insufficient in numbers to 

 cause at once important morbid changes ; they must have time to 

 undergo the necessary metamorphoses and to multiply within the 

 animal organism, and this time varies according to the number 

 of Schizophytes originally transferred to the condition or stage 

 of development in which they are transferred, and to the degree 

 of so-called predisposition or favorableness of conditions existing 

 in the infected animal. As a rule, the larger the amount of the 

 infectious material introduced and the richer the same in swine- 

 plague Schizophytes, the shorter the period of incubation, or stage 

 of colonization. 



On the other hand, if the infectious principle were a chemical 

 poison or virus, its action, one should suppose, would, under 

 all circumstances be exactly the same, and the malignancy 

 of the morbid process and the time required for its devel- 

 opment would not be influenced by, or be dependent upon 

 so many conditions, such as the individuality, age and tempera- 

 ture of the animal, the time and season of the year, the number 

 and stage of metamorphosis of the Schizophytes contained in the 

 infectious material and other yet unknown conditions. A poison 

 or virus, indestructible by water and air, and not affected by dilu- 

 tion, no matter how far it may be carried, one should suppose, 

 would act with great uniformity. Consequently one is obliged to 

 conclude that the Schizophytcs, and not a chemical virus, must, 

 and do, constitute the cause. 



11. The infectious principle undoubtedly consists in something 

 that is destroyed and made ineffective by putrefaction, because 

 infectious material, such as blood, blood serum, lung exudation, 



