284 Journal of the Department of Agriculture. 



the general level of veld infection is also reduced, and the risk attach- 

 ing- to overlooked carcasses of small animals will become negligible, 

 and may finally disappear altogether. 



Since the difficulties of completely clearing all carrion from the 

 veld are considerable, the margin of safety is increased by trying 

 to break the chain of causation of lamziekte at two points ihstead of 

 only one. The second point of weakness which the farmer can get at 

 immediately, is represented bv the depraved appetite or pica of the 

 cattle. 



Pica ob Depraved x\ppetite. 



It is a generally known fact that over large areas of South 

 Africa, cattle show an abnormal craving, particularly for bones. 

 Indeed the fact is so well known that farmers in many districts look 

 upon it as a natural thing and" only notice it when it becomes so 

 pronounced as to constitute a public nuisance, i.e. when the cattle 

 cong*regate around the homestead or Kaffir huts, devour the washing, 

 bags, clothes, riems, skins, and miscellaneous rubbish, and persist- 

 ently return when driven away. Such aciite manifestations are what 

 is understood ])y craving in the worst districts, and a man brought 

 up in such districts will quite ignore the subdued craving, manifested 

 only for bones, which is common on farms where pica is comparatively 

 mild. 



As already mentioned, the term pica, in the ordinary dictionary 

 sense, means depraved appetite of any sort, and of any origin. In 

 the human subject, for instance, it sometimes occurs as a concomitant 

 of ovarian disease. The general craving for rubbish is termed 

 " allotriophagia " and the distinctive craving for bones is termed 

 " osteophagia." The pica of the lamziekte areas is probably due 

 mainly to one cause (shortage of phosphorus), and its distinction 

 from other forms of pica must therefore be kept in mind. 



Un^derstanding the true connection between pica and lamziekte 

 as we now do, it is easy to realize why some sort of connection between 

 the two should have ])een so frecjuently surmised by the observant 

 farmer. In correspondence, farmers have frequently drawn atten- 

 tion to the fact that Avhen craving appeared lamziekte was not far 

 off. Indeed, Br. Hutcheon, of the old C^ape Veterinary Service, went 

 so far as to explain bone-eating as a definite premonitory symptom, 

 and to formulate a definite deficiency theory in which lack of lime 

 and jihosphate was held to be the cause of lamziekte. We now under- 

 stand exactly where his hj^pothesis breaks down, and although it 

 failed to explain lamziekte it can profitably be revived to explain 

 osteophagia. Hutcheon's vieAv, however, was empirically useful in 

 breaking a link of a then unknown chain, and it was made the basis 

 of bone-feeding experiments 1)y Borthwick and by Spriudl — Borth- 

 wiek at Wittelclayrug and S])ruell at Xoopmansfontein, distinctly 

 sliowing that if bone meal were sui)plied regularlv at the rate of three 

 Id four tables])oonfu1s a day, the mortality from lamziekte was 

 mateiially reduced. We now understand the full (connection ; bone 

 meal })reaks Link 4 (craving) of our etiological chain and Link I, 

 the primary cause (toxin), is accordingly separated. 



But the Hutcheon hypothesis failed to tliroAv any light on the 

 immediate cause of the disease and was abandoned when it was found 

 that craving and lamziekte were not iTivariably associated together; 



