THE VITAMINES IN THE ANIMAL KINGDOM 151 



hay, gave birth to a calf that was blind. The validity of the vitamine 

 hypothesis was tested in two ways. First, through a repetition of 

 Stead's experiments, by feeding to healthy animals the meat of 

 animals which had died of lamziekte, definite indication as regards 

 impoverishment of vitamine B could not be found. Secondly, the 

 influence of substances rich in vitamine B was studied. An addition 

 of orypan (extract of rice polishings) and yeast had no effect, and 

 we may therefore assume, with certainty, that lamziekte cannot be 

 caused by a lack of vitamine B. Experiments with other vitamines 

 were not tried. 



In the meantime, Theiler and his co-workers (447) have apparently 

 completely cleared up the etiology of lamziekte. They maintain that 

 in the etiology of this disease, six phases prevail, which are responsible 

 for its occurrence, and are related to each other, like the links of a 

 chain. 



1. A toxin or poison which causes the disease. 



2. Toxin-forming saprophytes. 



3. The availability of carcasses from which the toxins are formed. 



4. Pica, or abnormal craving, which leads animals to eat carcasses, 

 not present under normal conditions. 



5. The character of the vegetation and the soil (and climate) upon 

 which pica depends. 



6. Susceptibility of the animals to the toxin. 



The toxin was systematically investigated and seemed to be 

 similar to the botulinus toxin. It is very active, inasmuch as 0.00001 

 cc. per kilo body weight is a fatal dose. Lamziekte may also be 

 produced experimentally by administration of this toxin. The pro- 

 phylaxis and therapy consist of the elimination of one of the six 

 above mentioned links of the chain, at least theoretically. Practi- 

 cally, however, it seems that the best starting point is the pica and 

 since this condition is of greatest interest to us, we shall speak of 

 it in greater detail. 



Pica. It has been demonstrated in South Africa, that not only 

 cattle may exhibit this condition, but also ostriches, goats and 

 poultry. Pica is supposed to be a nervous ailment, which arises 

 only where the condition of the soil is such that the water quickly 

 passes through the upper layers. Because of this, the soil becomes 

 poor in phosphorus and hence produces a vegetation poor in this 

 element. Pica itself is not dangerous, but becomes so when the 



