INDIGESTION AND NERVOUS DEPRESSION, i-jc, 



is, in all probability, the respiratory movements. We have, indeed, in 

 the brain and spinal cord, a condition not unlike that which exists in 

 the fascia covering muscles, where the muscular substance during its 

 contraction presses flexibly the inner against the unyielding outer layer 

 of the fascia, and thus produces, in the space between them, a pumping 

 action. The skull and vertebral canal would correspond to the hard 

 outer layer or fascia ; and the brain and cord, which, as we know, ex- 

 pand and retract during the movements of respiration, when a part of 

 their bony case is removed, will have a similar pumping action upon 

 the cerebral spinal fluid to that of the muscle upon the lymph in the 

 fascia. 



In the case of the brain and the cord there will be, in addition, a 

 pumping action produced by the very circulation of the blood in them, 

 the alternate expansion and dilatation corresponding to the heart's 

 beats, having a similar effect to that produced by the respiratory move- 

 ments. As stimulation of the brain causes dilatation of its vessels, 

 and increases the flow of blood through them, mental action of itself 

 not only attracts more blood to the brain, but provides to some extent 

 for the removal of waste products. The movements induced by the 

 cardiac pulsations are not so extensive as those caused by the respira- 

 tory movements or by muscular exertion, and therefore, when the 

 brain is overworked, and the respiration and muscular movements are 

 underworked, the cerebral nutrition will be diminished by the imper- 

 fect removal of waste from its substance. But if, in addition to this, 

 the cerebral cells and fibers are actually poisoned by the circulation 

 within the vessels which supply them, of noxious substances due to 

 imperfect digestion or assimilation, matters will become very much 

 worse, 



"We have already seen how much the liver has to do with such a 

 condition. Now, while the brain is being taxed to its utmost, the 

 worker generally gets but very little exercise. The consequence of 

 this is, that although the respiratory movements still go on with regu- 

 larity, and the pressure of the diaphragm upon the liver at each respi- 

 ration presses the bile more or less out of the liver, yet the pressure 

 thus exerted is very much less than would be the case if the individual 

 were making occasional vigorous efforts during which the breath was 

 held, and the muscles of the abdomen put into action, as, for instance, 

 in springing from bowlder to bowlder on the moraine of a Swiss glacier. 

 So long as the brain-worker is exceedingly careful what he eats, so 

 that no excess of bile is formed, and is fortunate enough to escape 

 duodenal catarrh, so that no impediment, however slight, prevents the 

 flow of bile into the intestine, he may get along perfectly well ; but if 

 he be unfortunate enough to get what is commonly known as cold in 



II, 1, 13-18; " Centralblatt fiir Medicinischen Wissenschaften," ISYl, p. 514); Quincke 

 ("Reichert's und Du Bois-Reymond's Archiv," 1872, 153-177; "Centralblatt fiir Med. 

 Wissen.," 1872, p. 898). 



