PHYSIOLOGY. 



717 



that a watery exudation free from proteid is 

 formed in the glomeruli. and that this becomes 

 concentrated through the tubules, either by the 

 absorption of water and certain salts or by a 

 certain secretion of urea, uric acid, etc. The 

 process has been regarded as one simply of nitra- 

 tion by Ludwig, and as besides nitration involv- 

 ing the secretory activity of the glomerular endo- 

 thelium by Heidenhain. The experimental evi- 

 dence collected by E. H. Starling in his study of 

 the subject goes to show that the glomerular 

 epithelium may be looked upon as a simple filter- 

 ing membrane resembling in many particulars 

 a membrane of gelatin. When the pressure in 

 the glomerular capillaries rises above from 25 to 

 30 millimetres Hg, the measure of the osmotic 

 pressure in the capillaries, filtration takes place 

 through the glomerular epithelium, the filtrate 

 representing simply plasma minus proteid. The 

 higher the pressure in the glomerular capillaries 

 the more rapidly would this process go on. 



An account has been published by Prof. Emil 

 Fischer of his researches on uric acid' and the con- 

 stitution of the substances chemically related to 

 it, such as paraxanthine and heteroxanthine, 

 which are associated in urine; xanthine, adenine, 

 and guanine, which probably form part of the 

 nucleins of cells; and theobromine, theophylline, 

 and caffeine, the physiologically active constitu- 

 ents of tea, coffee, and cocoa. An accurate knowl- 

 edge of the constitution of these substances is, in 

 consequence of their relations, of great impor- 

 tance to physiologists, while a satisfactory pro- 

 cess for utilizing uric acid in the synthesis of 

 theobromine or caffeine would possess thera- 

 peutic interest as well as commercial value. Prof. 

 Fischer's studies have led to a clear knowl- 

 edge of the relationship that exists between these 

 complex products of animal and plant life, and 

 are believed to have made their commercial prepa- 

 ration possible. 



The action of pancreatic juice on proteids is 

 regarded as associated with an alkaline medium. 

 Some experiments bearing upon this point have 

 been made by B. K. Rachford, who, havrng ob- 

 tained the pancreatic juice from rabbits, employed 

 purified and dried blood fibrin for the determina- 

 tion of its solvent power, weighing the fibrin be- 

 fore and after the action of the juice had been 

 exercised upon it. In some preliminary experi- 

 ments he found, in opposition to Messrs. Chitten- 

 den and Albro, that when fresh rabbit's bile is 

 added to the fresh pancreatic juice of the same 

 animal, theproteolytic power of the juice acting 

 on neutral fibrin is stimulated to a marked de- 

 jrn-r. In most of the experiments the juice was 

 able to do one fourth more work by reason of 

 the presence of the bile, which is entirely in 

 favor of the value of alkalinity in promoting the 

 action of the pancreatic juice. The presence of 

 bile seems to limit bacterial action or the action 

 of organized ferments on the albuminous fer- 

 mentations. But when fibrin or other proteid is 

 ingested into the stomach it combines with a 

 certain proportion of hydrochloric acid, and 

 the author, in endeavoring to determine the ef- 

 fects of the addition of hydrochloric acid outside 

 the body, found that when fibrin was one half 

 saturated with hydrochloric acid (no free hydro- 

 chloric acid being present) it was as readily acted 

 upon by pancreatic juice as is neutral fibrin. 

 When, however, the fibrin was nine tenths satu- 

 rated with hydrochloric acid the proteolytic ac- 

 tion of the juice was retarded; whence the con- 

 clusion may be drawn that the acidification of 

 the proteid by the acid of the gastric juice to a 

 certain moderate extent does not interfere with 



the action of the pancreatic juice, though when 

 it is fully saturated the action is impaired. From 

 all the evidence Mr. Rachford has been able to 

 obtain he is led to believe that the conditions 

 which prevail throughout the small intestine in 

 carnivorous animals are everywhere favorable 

 to the proteolytic action of pancreatic juice. 



In continued experiments by Wakeli'n liarratt 

 on the discharge of water and carbon dioxide 

 from the surface of the body, the influence of 

 varnishing upon the aqueous discharge from the 

 skin was determined and the mode in which water 

 and carbon dioxide escape from the free surface 

 was further elucidated. It was fo.und that when 

 the skin is varnished the elimination of water is 

 diminished but not abolished, the diminution 

 amounting in the experiments to 78.1 per cent, 

 of the normal output. The behavior of the skin 

 in dry inflammation has been shown to be similar, 

 the diminution of output in this condition 

 amounting in the experiments made to 56.3 per 

 cent. In both cases the diminution is due to a 

 mechanical blocking of the sweat ducts. In 

 each case the incompleteness of the arrest of the 

 aqueous discharge from the skin is due to the 

 circumstance that this has a double origin: part 

 escapes by the sweat ducts, either by appearing 

 at their orifices or by diffusing from them into 

 the horny epidermis and being thence discharged 

 externally; the rest diffuses directly from the 

 rete through the horny epidermis into the ex- 

 ternal air, this being made possible by the prop- 

 erty which the horny epidermis possesses of tak- 

 ing up water in small amount. The water escap- 

 ing by the sweat ducts directly and indirectly 

 was found, in the experiments made, to be ap- 

 proximately equal in amount to that passing 

 through the horny epidermis from the rete. The 

 elimination of carbon dioxide by the skin is sim- 

 pler than that of water, being essentially a single 

 process, namely, that of diffusion through the 

 horny epidermis. 



It having been shown that after treatment 

 with alcohol the liver, the blood, and various 

 other tissues contain an amylolytic zymin, Noel 

 Paton undertook to determine whether the liver, 

 where amylolysis is so active during life, yields 

 a stronger diastase than the blood and other 

 organs after treatment with alcohol. Compari- 

 sons of the amylolytic activity of the liver, blood, 

 and kidney gave no evidence that the liver, after 

 treatment with alcohol, yields an amount of di- 

 astase in excess of that yielded by the kidney or 

 by the blood. Indeed, in several instances the 

 amylolytic activity of the blood and kidney was 

 found to be greater than that of the liver. The 

 amylolytic action of the liver after treatment 

 with alcohol is not proportionate to its action in 

 the fresh condition immediately after the death 

 of the animal, and is frequently more powerful. 

 So far the evidence we possess does not dispose 

 of the possibility that the zymin is a product of 

 the death and disintegration of cells. Even if 

 such evidence as we have of the actual exist- 

 ence of a zymin be accepted, the experiments re- 

 corded show that the part it plays in hepatic 

 amylolysis is uncertain. The idea that hepatic 

 amylolysis is due to a zymin is in the view of the 

 author strongly opposed by the observations re- 

 ferred to and by the experiments of Cavazzini. 



It is found by MM. Lannelonge and Gaillard 

 that the toxicity of the urine of children is in- 

 ferior to that of the urine of adults, but is largely 

 increased in cases of acute appendicitis. The 

 color of the pathological fluid is also more 

 marked, and its density and the amount of ex- 

 tractives present are greater. 



