STUDY OF POLYNEURITIS GALLINARUM. 455 



we may infer that the amount of vitamine required by man is 

 much less proportionately than that required by the fowl. 



The question of loss of weight also requires some elucidation. 

 It is quite apparent that if the metabolism of the entire nervous 

 system suffers from the loss of this vitamine, the rest of the body 

 tissues will also waste away as a result and there will be great 

 loss of weight. But how account for the loss of weight that 

 occurs in fowls fed on polished rice, but which have received this 

 substance in extract of rice polishings? It is believed that the 

 loss of weight in these cases may be due to the fact that the fowl 

 living on this diet is not in equilibrium of metabolism with regard 

 to other substances. For instance, it is quite possible that it is 

 suffering from a deficiency of fat, of phosphorus, of potassium, 

 and of other substances that are deficient in polished rice. This 

 is quite enough to account for the loss of weight in these cases. 



The cause of the great prostration in this disease should also 

 be considered. Some birds present this symptom while others do 

 not. We have seen that the degree of degeneration of the vagus 

 bears no relation to the degree of prostration of the fowl, and 

 that there is not sufficient change in the heart to account for the 

 sudden death. It is highly improbable that the prostration is 

 due to the peripheral neuritis. There are several possible expla- 

 nations of this phenomenon. Since the entire nervous system 

 is probably affected in this disease, we can easily suppose that 

 this general prostration occurs when the higher nerve centers 

 either in the brain or the cord are affected by the degenerative 

 process. 



On the other hand, a most attractive hypothesis presents itself 

 to account for this condition. Let us suppose that rice polish- 

 ings and other foods contain two substances or vitamines that 

 are essential for proper metabolism. One of these is the neuritis- 

 preventing substance, and the other a substance that prevents 

 general prostration, cardiac failure, etc. This hypothesis would 

 account for the three classes of symptoms observed in fowls 

 suffering from polyneuritis. Those cases belonging to class 1 

 evidently suffer from the deprivation of both vitamines. The 

 cases in class 2 suffer from deprivation of the neuritis-preventing 

 vitamine, but have received sufficient of the second vitamine 

 to prevent the occurrence of prostration; while those fowls in 

 class 3 have received sufficient of the neuritis-preventing vitamine 

 to defer at least the symptoms of nerve degeneration, but not 

 enough of the second vitamine to prevent their dying of general 

 prostration. This supposition would account for the three types 



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