770 



THE AGRICULTURAL JOURNAL. 



12 to 15 weeks, ulthough thiti period 

 seems to vary greatly in different cases, 

 and in a case recently reported from 

 India, one observer claims an immunity 

 of a year's duration in one of the animals 

 under his observation. Such proof of 

 immunity is difficult in cases where the 

 decision of such a point necessitates 

 periodical actual exposure to the disease, 

 which exposure, if successfully resisted, 

 will at the same time possibly strengthen 

 and prolong such immunity. 



Observers, however, seem divided in 

 their opinion as to whether the immunity 

 produced by bile can be extended by the 

 introduction of virus into the system 

 during the existence of such immunity. 

 That such should be the case without a 

 marked reaction seems improbable, for it 

 is— as far as we know at present — only 

 by such reaction that an immunity of a 

 high order can be produced. In most 

 instances the immunity attained seems in 

 direct proportion to the intensity of the 

 general reaction. Although we see in- 

 stances in which a high degree of im- 

 munity is conferred without marked 

 general reaction, as in the case of the 

 inoculation against quarter-evil, or vacci- 

 nation against small-pox. The apparent 

 local reaction following upon subcutane- 

 ous injection of gall does not seem to be 

 due in any measure to the specific action 

 of rinderpest-bile, as a similar swelling, 

 &c., follows the injection of normal bile. 

 This seems confirmed from the fact that 

 excellent results from bile, both from an 

 immunising and curative point of view, 

 have been obtained by injecting directly 

 into the jugular vein, and in such cases 

 no more reaction has been observable 

 than ihat which follows the introduction 

 of serum in a similar manner. Dr. Koch 

 was of the opinion that if animals re- 

 sisted the inoculation with virulent blood 

 during the period of bile immunity, that 

 their immunity was without doubt in- 

 creased. Such an opinion, however, does 

 not seem to have found favour with sub- 

 sequent workers ; in fact, the view has 

 been advanced by one worker of cons der- 

 able experience that the immunity, in- 

 stead of being strengthened, is modified 

 by the blood inoculation. While it is 

 difficult to see how this could be the case, 

 it is equally improbable that the introduc- 

 tion of the specific virus should give rise 

 to the formation of any protective prin- 



ciple in the system of an animal without 

 appreciable reaction. 



One of the systems of bile inoculation 

 which has been widely adopted in South 

 Africa in the past provides for the intro- 

 duction of l-5th of a centremetre (6 or 4 

 drops) of rinderpest blood upon the lOth 

 day after the first inoculation, which con- 

 sists of 15 c.c. of glycerinated bile. It is 

 claimetl that by this method a loss of 

 only 8 per.cent. has been experienced in 

 the treatment of many hundreds of 

 thousands of animals. This would seem 

 a practic^,l and satisfactoiy system of 

 immunisation, if evidence were forth- 

 coming, that the resulting immunity was 

 general throughout the herds so inocu- 

 lated. 



The question which ac once arises in 

 our minds is to what extent the bile 

 injection, ten days previously, had ren- 

 dered insusceptible the herd in question ; 

 for, from our knowledge of the immunis- 

 ing properties of bile, it seems probable 

 that a large percentage would be able, on 

 the 10th day after injection, to resist 

 without difficulty the introduction into 

 the system of a small quantity of virulent 

 material. 



The principle of inducing a mild form 

 of the disease during a condition of 

 partial susceptibility, and before a firm 

 immunity had become established from 

 the use of bile, would seem a good one if 

 all the animals of a herd were equally 

 susceptible, and could Ije looked to to give 

 uniform reaction after a certain lapse of 

 time. Such, however, we know unfor- 

 tunately not to be the case. 



While we are thus unable to gauge with 

 any exactitude the degree of immunity 

 established upon a given day after inocu- 

 lation in an individual beast, we are still 

 less able to forecast the exact duration of 

 the immunity, and the time at which the 

 beast will again commence to lapse into a 

 condition of susceptibility. This prevents 

 the adoption of any artificial measures to 

 ensure a modified attack about this 

 period. The suggestion to establish and 

 maintain the sickness amongst a herd in 

 which the immunity is expected to lapse 

 would seem a practical one, were it not 

 that such a measure could rarely be 

 adopted without cousidereble loss. If in 

 the animals of a herd, the immunity of 

 which was known to be lapsing, a close 

 contact with the disease could be ensured 



