LOCOWEED DISEASE OF SHEEP 433 



cially to be incriminated. These are usually most dangerous when in the stage of 

 advanced ripening and yet not fully matured, evidently indicating the development 

 of narcotic poison at this stage. Such poisons are found habitually in certain species, 

 like the chick vetch (Vicia cicera), which produces paralysis if fed to the extent of 



more than one-twelfth part of the ration With sound judgment and in 



well balanced rations, all such agents can be fed to advantage ; it is only when fed 

 exclusively or to excess as the heavy ration that they are to be feared. 



The symptoms of this disease are largely those of Marsh's loco disease, 

 though the disease runs a fatal course more rapidly than appears to be 

 usual in Marsh's cases. There is a fairly close resemblance between the 

 anatomical findings so far as can be judged by reading the accounts of the 

 two diseases. 



Law does not make the distinction very clear to the reader between 

 meningo-encephalitis and the epizootic cerebro-spinal meningitis of horses. 

 The latter disease is known in Idaho (Law), and both symptoms and ana- 

 tomic changes are largely those of the loco disease of Marsh. 



Hutyra and Marek (vol. 2, p. 624, &c.; and p. 634^645), differ somewhat 

 from Law in their description of the two last described diseases, the chief 

 difference being that they lay little stress upon the food, and attribute each 

 disease to a specific bacterium. In their discussion of the differential diag- 

 nosis (p. 632) they outline several diseases which would undoubtedly pass 

 for loco on the ranches. Until Marsh publishes his microscopic and bacter- 

 iological studies it will be impossible to decide whether Marsh's loco disease 

 is identical with meningo-encephalitis or with enzootic cerebro-spinal 

 meningitis, but in the meantime it seems rather more probable that Marsh's 

 disease is allied to meningo-encephalitis. 



F. THE LOCO PROBLEM. 



Crawford's review of the literature sets forth strikingly the state of 

 interminable confusion in which the loco problem has been involved since 

 the very beginning, a state due to the vagueness of the definition of loco 

 disease, and to the discrepancies in the description of symptoms, in the 

 statements of fact, and in the results of experiment. Crawford himself 

 decided that a poison can be extracted from some locoweeds but not from 

 others. This fact may yet be established in spite of Alsberg's contention 

 that the poison is not barium, a contention supported by Marsh. My 

 studies failed to reveal any indications that the animals were poisoned by 

 locoweed, while Marsh is fully satisfied that he has established the poison- 

 ous activity of locoweed beyond all doubt. Even Marsh found that eating 

 locoweed does not always produce loco disease, and he lays emphasis upon 



