52 THE LUNG PLAGUE OF CATTLE. 



normal textures of the full-grown. They partake, in common with em- 

 bryonic tissue, of an extraordinary impressibility to external influences^ 

 and a liability to destructive changes. These products of inflammation 

 are therefore presumably susceptible to the attacks of the pent-up germs, 

 just as the natural progeny of insusceptible animals are themselves sus- 

 ceptible without reference to the immunity of the parent tissues or system. 

 Again, the inflammation products are now open to the attacks of the 

 lung plague bacterium, just as the same products are more easily de- 

 stroyed by caustics and other chemical agents than are the sound tissues. 



It has been frequently noticed in Europe, that cattle which have ap- 

 parently recovered from the lung plague have been the vehicle for the 

 conveyance of the disease into new and previously healthy herds. In 

 several countries of Europe, accordingly, cattle that have passed through 

 lung-plague are branded on the horns with the letters L. S. (Lungen- 

 seuche). This serves the double purpose of publishing the fact that they 

 are not likely to contract the disease anew themselves, and that they 

 may, notwithstanding, convey it to others. 



One or two particular instances of the apparent conveyance of the 

 infection in this way may be here cited : 



1. In the Eecueil ile Medecine Veterinaire for March, 1879, M. Kabouam 

 records the case of a bullock brought from a stable where lung plague had 

 formerly prevailed, and suffering from a chronic discharge from the nose r 

 supposed to be due to bronchitis, but which ox introduced the lung 

 plague into the herd into which he was taken. 



2. The English cow which introduced lung plague into Australia, ac- 

 cording to one account, was probably a case of the same kind. She 

 was alleged to have suffered from lung plague in England, in 1857, and 

 had a relapse after her arrival in Australia in 1858, when she was the 

 means of infecting the entire colony. It may well be supposed that 

 this relapse may have been due to the great change of climate and gen- 

 eral surroundings to which this cow had been subjected, such change 

 being well known to renew the susceptibility to certain other diseases 

 after it had been worn out by a first attack. Thus strangles the dis- 

 temper of young horses which usually attacks the same animal but 

 once, has been known to attack animals thrice in succession, each time 

 after the subject had been removed from one country and climate to 

 another. Similarly the distemper of dogs has been known to attack 

 the same animal thrice, in England, Malta, and India, showing that the 

 example is not peculiar to one disease. That change of climate has a 

 potent effect on the system, is shown every day in the beneficial or per- 

 nicious operation on invalids who make a wide change of residence. 

 This influence is seen no less in the effect it has in counteracting the evil 

 effects of consanguinity. If the same family is bred closely, generation 

 after generation, in the same locality, sterility or other failure of vitality 

 soon interferes to cut short its career, but if brothers and sisters and 

 cousins are bred or reared under different conditions, their stamina is far 

 less likely to be undermined. 



The consideration of these points, and the woeful example of the infec- 

 tion of Australia, should lead us to guard against all such chronic cases 

 of this affection as carry encysted masses in the lung, and above all to 

 vigilantly exclude all animals imported in this condition, and all move- 

 ment of such animals from one part of the country to another. 



3. Mr. Braun, Loriiner street, Brooklyn, whose stables had been 

 healthy for months up to July 26, 1879, took in at this date a brown 

 heifer which had been removed from the infected Blissville distillery 

 stables January, 1879. This heifer was fat, plump, and, to all outward 



