MODE OF SPREAD. 277 



and caseation which are so common in tubercle do not 

 occur to the same degree in glanders, and typical giant 

 cells are not formed. The nodules in the lungs show 

 leucocytic infiltration and thickening of the alveolar walls, 

 whilst the vesicles are filled with catarrhal cells ; t'.e. t there 

 is reaction both on the part of the connective tissue, and 

 of the endothelium of the air vesicles, whilst at the 

 periphery of the nodules connective tissue growth is present 

 in proportion to their age. The tendency to spread by the 

 lymphatics is always a well-marked feature, and when the 

 bacilli gain entrance to the blood-stream, they soon settle 

 in the various tissues and organs. Accordingly, even in 

 acute cases it is usually quite impossible to detect the bacilli 

 in the circulating blood, though sometimes they have been 

 found. It is an interesting fact, shown by observations of 

 the disease both in the human subject and in the horse, 

 as well as by experiments on guinea-pigs, that the mucous 

 membrane of the nose may become infected by means of 

 the blood another example of the tendency of organisms 

 to settle in special sites. 



Mode of Spread. Glanders usually spreads from a 

 diseased animal by direct contagion with the discharge 

 from the nose or from the sores, etc. So far as infection 

 of the human subject goes, no other mode is known. There 

 is no evidence that the disease is produced in man by 

 inhalation of the bacilli in the dried condition. Some 

 authorities consider that pulmonary glanders may be pro- 

 duced in this way in the horse, whilst others maintain that 

 in all cases there is first a lesion of the nasal mucous 

 membrane or of the skin surface, and that the lung is 

 affected secondarily. Babes, however, found that the 

 disease could be readily produced in susceptible animals 

 by exposing them to an atmosphere in which pulverised 

 cultures of the bacillus had been. He also found that 

 inunction of the skin with vaseline containing the bacilli 

 might produce the disease, the bacilli in this case entering 

 along the hair follicles. 



