692 



PHYSIOLOGY. 



sations produced by 1,400 impacts of a toothed 

 wheel is but a finer quality of the roughness 

 produced by 30. We can no more be said to 

 distinguish 1,400 impacts upon the finger-tip 

 than to distinguish 256 vibrations when the 

 middle C is sounded upon the piano, although 

 we may know experimentally that exactly that 

 number of vibrations stimulate the ear. Let 

 us compare this sense of roughness with other 

 sensations. In sight we have a compass of 

 less than one octave, in hearing about eleven 

 octaves. Counting 30 as the lower and 1,400 

 as the higher number of impacts, we have 

 about five octaves of roughness. The utility 

 of this compass will, however, depend on the 

 smallness of difference in quality which it is 

 possible to distinguish. Very practiced musi- 

 cians are said to distinguish one sixtieth of a 

 tone; most persons far less. The author ex- 

 hibited an instrument intended to aid in the 

 investigation of the point under discussion, 

 upon which he said it was easy to calculate 



Eositions in which the fingers will be stiinu- 

 ited with the difference of any ordinary mu- 

 sical interval. 



The Circulatory System. Drs. Henry Sewall and 

 D. W. Steiner, of the University of Michigan, 

 have made studies of the action of the depress- 

 or nerve and of the effect of blood-pressure 

 upon the heart regarded as a sensory organ, 

 from which they infer that we may regard the 

 physiological relation of blood-pressure to car- 

 diac inhibition in a threefold light: first, in- 

 crease of arterial pressure directly stimulates 

 the inhibitory center in the medulla; second, 

 the same condition, by increasing resistance to 

 the heart's action, excites the inhibitory center 

 direct thro ugh the depressor nerve ; and, third, 

 elevation of arterial pressure brought about by 

 constriction of the peripheral blood-vessels 

 lessens the distention of the cardiac walls, in 

 which condition there is good reason to be- 

 lieve the local 'inhibitory apparatus is more 

 susceptible to influences reaching it from with- 

 out. They say, summing up the main results 

 of their work: "When the carotid arteries are 

 simply clamped, there is not a very considera- 

 ble rise of blood-pressure ; but when the same 

 operation is performed after previous section 

 of the depressor nerves, the rise of pressure is 

 very much greater, amounting to from 30 to 75 

 per cent, of the normal blood-pressure. The 

 fibers of the depressor nerve, through which 

 reflex inhibition of the heart may be brought 

 about, are stimulated at their peripheral end- 

 ings by the condition produced in the heart by 

 high arterial blood-pressure; and the coinci- 

 dent lowering of intra-cardiac pressure prob- 

 ably makes the heart more sensitive to inhib- 

 itory^influences proceeding along the pneumo- 

 gastric nerves." 



Nussbaum has published observations tend- 

 ing to show that there is in the animals he ex- 

 perimented upon a double supply of blood to 

 the kidneys : first, by the renal arteries running 

 specially to the glomeruli ; and, second, by the 



renal portal vein and the lumbar veins. He 

 concluded also that circulation through the 

 glomeruli could be wholly stopped by ligatur- 

 ing the renal arteries, and, believing that these 

 properties of the organ afforded a means of 

 determining the place of secretion of normal 

 and abnormal constituents of the urine, he en- 

 deavored to determine the constituents which 

 are secreted by the glomeruli and by the con- 

 vol uted tubes respectively. Nussbaum's results 

 have been generally accepted ; but J. G. Ada- 

 mi recently, in repeating his experiments, was 

 unable to obtain his results, and more extended 

 observations led to the conclusion that the ana- 

 tomical basis of his work was not sound, and 

 his method was not suited for any exact deter- 

 mination of the passage of substances through 

 the kidneys. Mr. Adami's own experiments 

 on the nature of the glomerular activity show 

 that the arterial supply of the kidneys may be 

 cut off, and nevertheless, a collateral circula- 

 tion being set up, a certain amount of blood- 

 flow will be going on through the glomeruli. 

 It probably takes place through branches of 

 the renal artery running direct to the capillary 

 net-work round the tubules. The phenomena 

 are such as can be fully accounted for on the 

 supposition that a gradually improving circula- 

 tion of this kind in connection with the glom- 

 eruli has been established. The details of the 

 experiments also go to show that the glom- 

 ernlar epithelium may be regarded as possess- 

 ing powers of a selective secretory nature; 

 that a diuretic may exert a direct action upon 

 the glomerular epithelium ; and that the secre- 

 tion of albumen out of the blood by the glom- 

 erular epithelium may occur in normal condi- 

 tions. 



In experiments on the connection between 

 the coloring-matters of blood, bile, and urine, 

 C. A. MacMunn has found that chloroform fur- 

 nishes an excellent means of separating the acid 

 hsematin formed by the action of alcohol acidu- 

 lated with sulphuric acid upon blood, and de- 

 scribes, in the " Journal of Physiology," a pro- 

 cess by which he applies that agent. At the 

 conclusion of the operation there is left as a 

 residue a dark-brown pigment, soluble in alco- 

 hol, ether, chloroform, aqueous alkaline solu- 

 tions, and bisulphide of carbon, and insoluble 

 in petroleum and water. If left alone for some 

 time, it dries up into a bluish-black powder. 

 This residue can be used for preparing solu- 

 tions showing the spectra of acid hgematm, 

 alkaline hgematin, hsemochromogen, and hce- 

 mato-porphyrin, according to the solvents and 

 reagents to which it is exposed. In the bile of 

 the sheep and ox the author has found a pig- 

 ment which he considers should be distin- 

 guished from other pigments, and he gives it 

 the name of cholohaBmatin. In the snrae pa- 

 per in which these results are given, Mr. Mac- 

 Munn describes his investigations of the color- 

 ing-matters in bile from a biliary fistula ar.d 

 the coloring-matters of faeces and urine. 



Prof. Du Bois-Reymond, speaking of the dim- 



