Contagious Pneumonia hi the Horse. 143 



In view of the frequent persistence of this malady in a given 

 stable for a great length of time, successive animals being attacked 

 at long intervals, and where isolation was impracticable, Beck- 

 mann rubbed the nasal discharges of the sick on the nasal mucosa 

 of the unaffected, producing the disease almost invariably in a 

 mild form. The infected animals were placed in the best hy- 

 gienic conditions, the duration of the infection was shortened, 

 and the horses being rendered immune, the stable was then disin- 

 fected with a satisfactory result. 



Schiitz, Hill, Pilz and a number of others have sought artificial 

 immunity, by the injection of blood serum from a horse that has 

 recently recovered from the malady. The results were very con- 

 tradictory. In some cases the disease came to a sudden end. In 

 other stables no new cases appeared either in those treated with 

 serum or in those left without treatment. In other experiments, 

 new cases occurred among those treated with the serum ; — in 

 Weishaupt's cases after a lapse of one or two months. This is 

 exactly what might be expected. If the horse supplying the 

 blood-serum had really recovered, and if the microbes (strepto- 

 cocci) had disappeared from the blood, the latter would of neces- 

 sity retain little of the toxins, but much more of the antitoxins, 

 the active production of which would be continued by the stimu- 

 lated leucocytes. These antitoxins would neutralize the toxins, 

 in case of invasion and prevent that from reaching the maximum 

 of intensity that it would otherwise have reached, but would be 

 powerless to stimulate the leucocytes of the inoculated animal into 

 the habit of themselves producing antitoxins. This would act 

 rather as a curative than a prophylactic agent, and its value would 

 be spent as soon as the injected antito"5iins were eliminated from 

 the system. 



The true line of inquiry would have been, whether injection of 

 the toxins, which acting on the leucocytes would have stimulated 

 these to the habit of producing antitoxins in large amount, might 

 not be expected to give an immunity as lasting as that which 

 follows on a casual attack of the disease. , I^ignieres appears 

 to have approximated to this, in his experiments on mice 

 and rabbits. In horses suffering from contagious pneumonia it 

 lowered the temperature, but did not materially affect the result 

 of the attack. If we adhere to Lignieres' own theory of causa- 



