13 

 " invariably, in out experience, consisting of horses tested when in the incipient 

 stages of Glanders, or at any rate when but slightly affected, as evidenced by 

 the fact that their original reactions, though typical, are nof as w,ell marked 

 either thermally or locally, as those given by clinical cases or by these animals- 

 which, while perhaps not showhig external symptoms, are suffering from the 

 disease in an advanced form. ■ 



, 3. Those which, having on one or more occasions definite-ly reacted,. 

 dejv'elop an. acquired -tolerance to the test, the latter being, however, of a. 

 temporary character, so that after the lapse of a varying period, generally from. 

 six to twelve months, a typical reaction again follows the injection of Mallein. 



The first-mentioned class are of hut little importance, and demand no- 

 attention at our hands beyond a due consideration of the part they have already- 

 played, and doubtless #ill for sOme time continue to play, in promoting boot- , 

 less discussion, and thus, to some extent, retarding the general adoption . of 

 Mallein as an authoritative diagnostic agent. 



The various causes which contribtite'to their being wrongly classified as- 

 reactors will, however, be shortly dealt with when We take up the question of 

 reactions typical and atypical. > ' . ' 



The second class is naturally much more interesting, consisting as it does 

 of horses which actually overcome the infection of Glanders ,either through; 

 the action of Mallein or by the efforts of nature unaided, or at least aided only 

 by favourable phy.sical conditions. . , ~ 



We have in Canada under supervision at present a considerable number- 

 of horses whic)i have at one time or another, during the past four years, given 

 a typical rea.ction to Mallein, but which are now, so far as we can ascertain; by' 

 periodical inspection and repeated testing, absolutely free from' Glanders. Thcse- 

 animals, however, constitute a lamentably small proportion of the total number- . 

 wliich reacted without showing clinical sympto^ms in the two years during" 

 which we -followed the retesting system. Two years ago I stated that about 

 '25 per cent, of our non^clinical reactors had ceased to react, and were appar- 

 ently free" from Glanders. At that time I expressed my great disap-pointment , 

 with the small return which this percentage gave for the, risk and labour- 

 involved in carrying on the retests, and announced that it was our intention to- 

 discontinue that' method of dealing with Glanders and adqpt the plan whicfr 

 we are now following. ^ 



I am sorry to have to tell you that in cla.ssing all these horses as safely- 

 ceased reactors vve were seriously in error. -During the intervening period a-- 

 , considerable number of them have rejoined the reacting ranks, and, have been 

 condemned as diseased. There are still, however, a number which have con- 

 tinued, to stand hot only the Mallein test, but the test of time. These give- 

 absolutely no'indicatipn of beirg'other than healthy horses, and thus, so far as- 

 caribe seen at present, there is no reason to doubt^that, in a proportion of com- 

 paratively mild cases of Glanders, recovery may and does take place. 



We have found, moreover, that while it is not by any. means- possible to- 

 tell at the first, or even, at the second test which of the afifected horses will' 



