484 Veterinary Medicine. 



toxicity of the marc is higher in certain years, and in tlie product 

 of certain fields, than in others, and this is in keeping with the 

 effect of environment in modifying the products of a plant. The 

 increased production of chlorophyl under the action of sunlight is 

 associated with a material increase of the amount of solanin. 

 Until therefore another toxic product can be shown to be the es- 

 sential cause of this affection the solanin must be charged with 

 this result. This conclusion would be more inviolable if the 

 animals attacked showed other symptoms of solanin poisoning 

 such as narcotism, vertigo, stupor and paralysis, and the absence 

 of the.se may perhaps be due to the gradual advance of the toxic 

 action, and the progressive immunizing of the animal system. 

 The brain may be able to accommodate itself more readily than 

 the skin. 



The other constituents of the potato or of the marc fail to pro- 

 duce the eruption under other conditions : the alcohol in brewers 

 and distiller's grains, the acetic, lactic and butyric acids in the 

 refuse of starch, beet sugar and canning factories, the potash in 

 turnips and other roots, the yeast ferment in brewers' grains. 

 The acarus of foot mange (symbiotis bovis) is rarely present in 

 the affected animal though the eruption in the same situation 

 would strongly suggest its presence and lead to a search for it. 

 Moreo\ er the eczema appears at once in a large number of ani- 

 mals, affecting a large area without evidence of slow and steady 

 progression and disappears with equal rapidity in many cases 

 when the diet is changed. Finally the eczema has not been suc- 

 cessfully propagated bj' inoculation which conveys mange in- 

 fallibly from animal to animal. 



Symptoms. The disea.se is associated with slight fever, cos- 

 tiveness, impaired appetite, hypersemia of the mucosse, epiphora, 

 viscous salivation, muscular weakness, and finally emaciation 

 and black diarrhcEa. The gravity of these symptoms varies, 

 being greater when the animals have eaten the leaves and stems, 

 the raw potatoes in their .skins, the young shoots and parings, or 

 green potatoes which have been sunned. The animals may lie 

 mo.st of their time stretching themselves out with head extended 

 on the ground, they may grind the teeth, may have pulse small 

 and rapid, tympany, lethargy, coma and even paraplegia but 

 these severe symptoms are exceptional and almost altogether 



