ECZEMA. 



517 



IS well known ; we have observed it upon a horse, in which case 

 large doses of bromide of potassium had been administered : a gen- 

 eral eruption shows itself, which is mild on the trunk, and very- 

 intense, on the contrary, upon the extremities. 



Opinions advanced on the subject of the nature of the toxic 

 matter which produces eczema are not based upon any positive 

 facts. The following chemical principles contained in the residues 

 or in the potato itself have been in turn accused : 



1. Solanine or solanidin. The affection has been looked upon for 

 a very long time by some authors as a poisoning from solanine. 

 In support of this theory, they claim an increase of solanine in po- 

 tatoes at the time of germination of the plant and the relative 

 frequency of the disease in animals which are fed with germinating 

 potatoes or with their residues. But in malt or residue eczema we 

 do not observe the symptoms of accidental or experimental poison- 

 ing by solanine, such as narcotism, staggering gait, stupefaction, 

 paralysis, etc. (see Poisoning by Solanine); on the other hand, 

 potatoes which are not yet undergoing germination, and which 

 consequently do not contain any solanine, may also cause this 

 disease. 



2. Inferior alcohols produced at the same time as spirits of wine. 

 They are found in all inoffensive malts, especially in those of rye; 

 again, the residues of potatoes which are given to animals are 

 almost always free from alcohol ; moreover, these do not exist in 

 potatoes which are in process of germination. Finally, all the 

 symptoms of intoxication by inferior alcohols are altogether differ- 

 ent from those of malt disease. 



3. The acids contained in potato residues (acetic, lactic, or 

 butyric acids). They are also found in other residues, while they 

 do not exist in potato stalks. The proportion of these acids, too, 

 is extremely variable, and inoffensive malts are often quite loaded 

 with them. 



4. Johne has thought himself able to establish the relation of 

 cause and effect between the potash salts contained in the potato 

 and eczema, but nothing justifies this hypothesis : the potash com- 

 pounds are muscular poisons, and their presence in a large pro- 

 portion in alimentary matters is not injurious. 



Other theories upon the nature of malt eczemas. 

 1. According to Ziirn, the fermenting cells (Sprosshefezellen) of beer 

 yeast are transformed into batonets in the intestinal canal, which, 



