The Cause aKd Prevention of Lamziekte. 225 



does seem to exist in parts of South Africa — on most Natal farms, for 

 instance — and presumably exists in those countries where pica is 

 reported but where lamziekte is not recognized. But if an animal 

 leaves a lamziekte area and dies soon after in a clean area, its own 

 carcass (Link 3) ma}' serve as pabulum for the multiplication of the 

 toxicogenic saprophytes (Link 2) introduced into its own intestine 

 while grazing on the lamziekte region. Toxic material (Link 1) 

 maj' then be produced and a large number of organisms scattered 

 around the immediate vicinity. If this .happeils in a district where 

 conditions (Link 5) are such that pica (Link 4) is prevalent, a new 

 focus of lamziekte may be set up and the disease so appear in an area 

 in which it was previously- unknown. 



It does not necessarily follow that an animal so dying will 

 reproduce large numbers of the toxicogenic saprophytes, but it Tnay, 

 and certainly often docs. Other factors, as not yet fully understood, 

 also govern the decomposition of carcasses and regulate the extent 

 to which a live animal can scatter Link 2. If the organisms are so 

 introduced into a new area they may remain in the soil for some time 

 after the carcass has decomposed and is no longer toxic, but if they 

 get no chance of perpetuating tliemselves by infecting a fresh carcass 

 they probably die out in time, under competition with the normal soi-l 

 bacteria and protozoa. If, on the other hand, animals are dying in 

 tlie ncAv area from otlier causes, such as drought, fresh carcasses may 

 become infected and the lamziekte organisms thus be multiplied. If 

 for some reason pica is present in the new area, but is not acute, the 

 mortality from lamziekte may remain low, appear in some years and 

 not in others (Link 5), and possibly even disappear altogether. 



With this short illustration of the interaction of the different 

 factors involved, we may proceed to consider in more detail a few of 

 the asjjects of tlie experimental work of the year which has elapsed 

 since the present explanation was first propounded. 



For this purpose we may take the links in the order in which 

 tliey were enumerated, at the same time indicating their inter- 

 dependence upon one another by overlapping in the discussion. 



The Toxix. 



We have stated that the eating of carrion causes lamziekte, and 

 it may again be emphasized that any sort of carrion may serve as 

 origin of the toxin. It happens that rotten bones are probably the 

 most frequent source actually ingested by the cattle, but this does 

 not mean that such bones are more toxic than other carcass material. 

 It merely means that bone material is less obnoxious, and that even 

 those animals showing the most depraved appetite will pick and 

 clioose when they get the chance. The pica is dominantly an " osteo- 

 phagia," i.e. a craving for bones, and if the cattle -3an gratify it with 

 bones they will, generally speaking, not touch anything else. 

 Indeed, unless osteophagia is acute they will select the sweetest bones 

 thay can find. 



When pica is very bad, cattle will blindly attempt to satisfy it in 

 all sorts of ways and go for hide, dried fragments of flesh, coal, rags, 

 and even tins. The scientific name of this form of craving is " allo- 

 triophagia," i.e. a craving for all sorts of unusual things, as distinct 

 from " osteophagia " or bone-craving proper. But generally' the 



