Eczema of Alimentary Origin in Cattle. 493 



potatoes are largely used, for distillation and the production of 

 starch, herds of cattle are fed often almost exclusively on the re- 

 fuse or marc, and in such herds an eczematous eruption of the 

 legs and exceptionally .of the body is a familiar occurrence. 



Causes. The disease has been definitely traced to an exclusive 

 dietary on potato marc, and still more so to the skins, to tubers 

 rendered green by exposure to the sun, and to the distillery 

 potato refuse which has undergone fermentation. Thus 80 litres 

 of the pulp daily without dry food will determine a violent attack 

 in the animal consuming it, while the animal consuming 40 litres 

 has it much milder (Friedberger and Frbhner). It attacks ani- 

 mals living in the best conditions of cleanliness and pure air, 

 and the essentially toxic quality of the cause may be deduced 

 from the fact that newly bought animals, which are not yet habit- 

 uated to it suffer the most, that fattening cattle are the common 

 victims, while work oxen which perspire more freely and milch 

 cows escape, yet calves fed upon their milk may suffer from diar- 

 rhoea and infants from a cutaneous eruption ( Johne) . The poison 

 it is to be inferred is eliminated in the milk. Similar examples 

 of the protecting of the milch animal by elimination of the poison 

 through the milk are found in bean trefoil (cytisus) which 

 poisons the milk while proving harmless to the goat which yields 

 it, and the poison of milk sickness which is deadly to cattle which 

 are not giving milk, and harmless to the milch cow, yet deadly to 

 those that consume her milk. 



The exact nature of the poison is as yet uncertain, and as 

 solanin is the only toxic principle so far discovered in potato, 

 this has been held tentatively to be the essential cause. The 

 amount of solanin in ■ young and germinated potatoes has been 

 given by Cornevin as follows : 



Germinated tubers Young tubers. 

 The entire tuber contains 0.21 o. 16 



The central fleshy part 0.16 0.12 



The parings and pickings o 24 o, 18 



The toxic strength of the marc is not impaired by boiling, 

 cooking or other culinary treatment, and the same is true of 

 solanin. The toxicity is greatest after the potato has been sub- 

 jected to germination, or when it has become green by exposure 

 to the sun, and in these conditions the solanin is increased. The 



