PHYSIOLOGY. 



675 



An experiment carried out by Zuntz and 

 "Wolff goes to show that any one can dimmish 

 Ins weight by taking a deep inspiration. The 

 experiment is most striking when the subject 

 is standing on a decimal balance, which is so 

 arranged that it can only give a kick upward. 

 In this case the pan with the weights in it 

 sinks when the inspiration is taken. The phe- 

 nomenon is explained as being the result of 

 the sudden straightening of the spinal column 

 and elevation of the head which occurs in tak- 

 ing the inspiration. The head, by its momen- 

 tum, carries the lower part of the body slightly 

 with it, so that the latter presses less forcibly 

 on its support. 



Experiments by Dr. Loewy indicate that the 

 respiratory center in the medulla oblongata is 

 able to maintain the rhythm of the respira- 

 tory movements after the nerve is separated 

 from both the brain and the peripheral parts 

 of the vagi. Moreover, the center when thus 

 isolated was found to be equally susceptible to 

 stimuli, whether applied directly or arriving 

 from the periphery, as when it was still con- 

 nected with the brain and lungs. 



Sydney Ringer, investigating the action on 

 fish of distilled water alone and of distilled 

 water holding inorganic salts in solution, found 

 that the fish soon died when placed in distilled 

 water, not because of the absence of air, but of 

 the absence of salts in the water. To ascertain 

 in what manner the destruction of the fish is 

 brought about, the author tested the action on 

 the gill-edges of fresh-water mussels of distilled 

 water alone and of distilled water containing 

 various proportions of salts. Distilled water 

 soon destroyed ciliary action, causing the cells 

 to swell often to quadruple their natural size, 

 so that many burst and liberated their nuclei. 

 The distilled water also separated the cells, and 

 caused complete disintegration of the tissue, 

 separating them from one another, and seeming 

 to induce swelling of the cement material which 

 united them. It was therefore evident that 

 distilled water, in part at least, will destroy 

 life by disorganizing the gills and impeding res- 

 piration. Further experiments made it proba- 

 ble that this disintegration of the structure and 

 the consequent death of the fish were caused 

 by both osmosis of the cells and imbibition by 

 the material uniting the cells to one another. 

 The swelling and other effects were checked 

 by the addition of minute quantities of various 

 salts to the water. 



Digestion. R. H. Chittenden and Herbert E. 

 Smith, having studied quantitatively the modifi- 

 cations, under various conditions, of the dia- 

 static action of saliva, conclude that such action 

 can be taken as a definite measure of the 

 amount of ferment present only when the dilu- 

 tion of the saliva in the digestive mixture is 

 1 to 50 or 100. The limit of dilution at which 

 decisive diastatic action will manifest itself 

 with formation of reducing bodies is 1 to 2,000 

 or 3,000. The diastatic action of neutralized 

 saliva is greater than that of normally alkaline 



saliva. The difference is particularly noticea- 

 ble where the dilution is as 1 to 50 or 100, and 

 is apparently out of all proportion to the 

 amount of alkalinity. Sodium carbonate re- 

 tards the diastatic action of ptyaline in propor- 

 tion to the amount of alkaline carbonate pres- 

 ent ; but its destructive action is modified ma- 

 terially by the dilution of the saliva, becoming 

 greater the more the fluid is diluted. Neutral 

 peptone has a direct stimulating effect on the 

 diastatic action of neutral saliva. The presence 

 of small percentages of that agent tends to 

 raise the diastatic action of normally alkaline 

 saliva to a point beyond the action of the neu- 

 tralized fluid. Peptone tends likewise to di- 

 minish the retarding action of the various per- 

 centages of sodium carbonate. It tends to pre- 

 vent the destructive action of dilute sodium 

 carbonate on salivary ptyaline, thus giving proof 

 of the probable formation of an alkaline-proteid 

 body. Saliva, with its proteid matter saturated 

 with acid, appears to have a greater diastatic 

 action than when simply neutralized, except 

 when the acid-proteids thus formed are above 

 a certain percentage. Small percentages of 

 peptone saturated with acid similarly increase 

 the diastatic action of neutralized saliva up to 

 a certain point. Increasing the percentage of 

 acid-proteids may cause almost a complete de- 

 struction of the ferment. The most favorable 

 condition for the diastatic action of ptyaline, 

 under most circumstances, appears to be a neu- 

 tral condition of the fluid, together with the 

 presence of more or less proteid matter. The 

 addition of hydrochloric acid, however, to di- 

 lute solutions of saliva, giving thereby a small 

 percentage of alkaline proteids, appears still 

 further to increase diastatic action. Three thou- 

 sandths per cent, of free hydrocloric acid almost 

 completely stops the amylolotic action of ptya- 

 line. The larger the amount of saturated pro- 

 teids, the more pronounced becomes the re- 

 tarding action of free acids. The retarding ef- 

 fect of the smaller percentages of free acid are 

 not wholly due to destruction of the ferment. 

 Pronounced destruction takes place with from 

 0.005 to 0.010 per cent, of free hydrochloric 

 acid. Proteid matter, in influencing the dias- 

 tatic activity of salivary ptyaline, acts not only 

 by combining with acids and alkalies, but appar- 

 ently also by direct stimulation of the ferment. 

 Mr. Schneitzer, of Kansas City, has found 

 that pancreatine and pepsine act with perfect 

 case and freedom in presence of each other. 

 When digested together they do not destroy 

 one another, nor do they lessen each other's 

 digestive activity in whatever proportion they 

 may be digested. Long- continued exposure to 

 heat and moisture injures their original ac- 

 tivity. Digested in acid or alkaline solutions 

 the injury is increased. Pancreatine, when di- 

 gested for some hours in an acid solution, be- 

 comes permanently injured or destroyed, and 

 pepsine, when digested in an alkaline solution 

 for some hours, is also permanently de- 

 stroyed. But such a state as prevails in the 



