460 METABOLIC ABNORMALITIES, AUTOINTOXICATION 



at least in part, upon the effect of these acids upon the muscle 

 tissue, for Lee found that /9-oxybutyric acid causes the same 

 fatigue reaction in muscles as does sarcolactic acid. Further- 

 more, sarcolactic acid itself often appears in the urine in these 

 conditions. It may be added that in fatigued animals the 

 alkalinity of the blood (by titration) has been found decreased 

 (Geppert and Zuntz), and the proportion of the urinary nitrogen 

 that appears in other combinations than urea is increased 

 (Poehl !). 



The " Toxins " of Fatigue. In extreme exhaustion 

 the evidences of a general intoxication often become severe, so 

 that the condition may resemble an acute febrile disease and 

 last for several days. It seems very probable that substances more 

 toxic than the above-mentioned acids are involved. Weichardt 2 

 claims to have demonstrated as produced by muscular fatigue a 

 toxic substance, which in structure resembles the bacterial toxins, 

 and against which an antitoxin may be obtained. This toxic 

 material is, he believes, formed from the proteid molecule in the 

 first stages of its decomposition, as a side product which is 

 normally protected against by a formation of an antitoxin, rather 

 than by being split up further, as is the case with the rest of the 

 proteid molecule. 3 Whether this work is confirmed or not, there 

 remains the fact that the blood of fatigued animals contains 

 toxic substances, which Mosso proved as follows : If blood is 

 transfused from an exhausted dog to a normal dog, from which 

 an equivalent amount of blood has been withdrawn, this second 

 dog will show the usual manifestations of fatigue. 



Mental Fatigue. The chemical changes of mental fatigue 

 are not known, but it is known that the ganglion-cells show 

 marked structural alterations as a result of fatigue, chroma- 

 tolysis often being very striking. Since lecithin forms so im- 

 portant a part of the nervous system, it is tempting to imagine 

 that in fatigue excessive quantities of its toxic decomposition- 

 product, cholin, and the still more toxic derivative of cholin, 

 neurin, are formed in considerable amounts and cause part, at 

 least, of the intoxication. Cholin has been demonstrated by 

 Halliburton and Mott and their co-workers, in the cerebro- 

 spinal fluid, and also sometimes in the blood of patients suffering 

 from organic nervous lesions, including such conditions as dis- 

 seminated sclerosis, tabes dorsalis, progressive muscular atrophy, 



1 Deut. med. Woch., 1901 (27), 796. 



2 Munch, med. Woch., 1904 (51), 12 and 2121; 1905 (52), 1234; also re- 

 viewed by Wolff-Eisner, Cent. f. Bakt, 1906 (40), 634. 



3 Weichardt, Munch, med. Woch. 1906 (53), 7. 



