GLANDERS. 483 



into the Southern States from Cuba, which was a hot-bed of that 

 disease, with a disastrous result which might have been easily pre- 

 vented (p. 489). 



PERIOD OF INCUBATION.— This period is stated to vary 

 from three to nine days. The period of apparent latency is much 

 longer, and may extend to months, if not years. Such instances of 

 seemingly^ prolonged incubation are due to the fact that the 

 disease is confined to the lungs and other organs hidden from 

 view. As a rule, the longer the period of incubation, the less 

 virulent will be the attack. It is probable that glanders does not 

 take longer than eight days to establish itself in the lungs. 



COURSE. — Before the invention of mallein (p. 626), glanders 

 was recognised only by its outward symptoms, and was regarded 

 as a. very severe and nearly always an incurable disease. Instances 

 have occurred of horses with outward signs of glanders (p. 487), 

 and especially of farcy, having apparently recovered. " When the 

 mallein test is applied to a large stud of horses among which 

 glanders has existed for several years, it frequently happens that a 

 notable proportion of the animals react — perhaps 20 per cent, or 

 more — ^although for a number of years previously, the proportion 

 of animals which have developed symptoms of the disease, may 

 have been very much smaller than that. It is this experience which 

 justifies the view that, apart from any curative effect of mallein, 

 many cases of glanders run a mild course, and ultimately end in 

 complete recovery" (McFadyean). 



The microbes of glanders are taken up by the blood-vessels, what- 

 ever their port of entrance into the body may have been, and their 

 presence in various tissues causes the formation of nodules 

 (tubercles) which may become converted into abscesses and ulcers. 

 The lymphatic vessels of an affected part become filled with 

 virulent material (their office being to remove waste products), 

 and consequently they become inflamed. The form taken by 

 the disease depends on the 'part in which nodules appear, as, for 

 instance, the lungs and air-passages in glanders ; and the skin 

 in farcy. 



The apparent reason for the submaxillary glands (the glands 

 between the branches of the lower jaw) becoming affected, when 

 ulcers form inside the nostrils, is that they receive the lymphatic 

 vessels of the nasal cavities, and consequently become inflamed 

 by the microbes which are brought to them by these vessels. The 

 rise of temperature is due to the hea1>producing products (p. 447) 

 manufactured by the microbes of this disease. 



When recovery sets in, the tubercles dry up, harden, and become 



31* 



