The Cause and Prevention of I.a.mziekte. :22;) 



in different fasliion here. The etiological chain may, for purposes 

 of popular exposition, be shown in six links, enumerated as 

 follows : 



1. The toxin which poisons the animal. 



2. The toxicogenic saprophytes whioli elaborate the toxin. 



o. The carcass material out of which llie loxin is manufac- 

 tured. 



4. The pica (^allotriophagia, osteophagia) or depraved appetite 



which impels the animal to eat decomposing matter which 

 it would otherwise shun. 



5. The vegetation which produces the pica, ihe soil upon which 



that vegetation grows, and the climate of the district. 

 G. The susceptibility of the animal concerned, towards pica 

 and towards the toxin. 



In considering lamziekte only as a naturally contracted disease 

 of cattle this last link falls away, since all cattle are susceptible to 

 the toxin and nearly all cattle are susceptible to pica, although the 

 degree of abnormal craving is partly a question of individual 

 idiosyncrasy. But it must not be forgotten that goats, ostriches, 

 and poultry can also contract lamziekte naturally, and that one of 

 the first consequences of the discovery was the proof that nearly all 

 animals could develop lam/iekte experimentally. The disease has 

 been produced experimentally in horses, sheep, goats, rabbits, guinea- 

 pigs, ostriches, and ducks, and could doubtless be produced in man, 

 if any of our staff were bold enough to try the experiment. 



With ostriches and poultry Link 4 of the etiological chain 

 is unnecessary, since they do not need to display pica, but may 

 pick up fragments of toxic bones or carrion in the ordinary course 

 of events. Fortunately, they are less susceptible to the toxin than 

 are cattle. Goats occasionally eat " pensmist " permeated with toxin 

 from the carcass, and so contract lamziekte without necessarily 

 showing pica. It has also been reported that donkeys are occasionally 

 observed to eat " pensmist," in which case stray cases of natural lam- 

 ziekte in donkeys are easy to understand. 



It is also interesting to mention that rats appear to be very 

 resistant to the toxin ; in more than one case a rat being found to 

 stand a dose big enough to kill an ox. This is fortunate for the rat, 

 since — although one does not speak of it as possessed of depraved 

 appetite — hunger may drive such, an omnivorous animal to- eat toxic 

 material. 



Sheep are very susceptible to the toxin, and the only reason why 

 they do not contract lamziekte naturally is that they do not develop 

 the comparatively trivial "osteophagia" or "bone-craving," even 

 iliough exposed to the same veld conditions as the cattle. The 

 growing practice of stocking the lamziekte areas Avith sheep, simply 

 l)ecause cattle could no longer be reared profitably, now finds its 

 explanation not in the fact that sheep are immune to lamziekte. but 

 in the fact that they are not " bone-eaters." 



At this point it should be pointed out that the practice of rearing 

 sheep alouf/ with, cattle on the lamziekte areas has in the past 

 increased the incidence of lamziekte amongst the cattle. The sheep. 



