I'lIYSlOLOGY. 



651 



than pepper, while cloves and cinnamon were 

 distinguished. I>iflVrences of 1 of temperature 



i-ily rocogni/od. 



It has Keen discovered that after chewing the 



>f (fymnema sylvestre, an asclepiad plant 



of India and Africa, sugar no longer excites a, 



sweet ta-te. L. E. Shore has found that the 



hitter ta>te is also easily prevented by this sub- 



stai , nut not so readily as the sweet taste of 



glycerin. An analysis of the dried leaves of this 

 plant I iy Hooper showed that an organic acid 

 was present, which, having obtained it in a crude 

 state, he considered allied to chrysophanic acid 

 and named gymnemic acid. It occurs to the ex- 

 tent of 6 per cent, of dried leaves. 'Hooper 

 found that the action of the leaves of the plant 

 on taste was due to this body ; and Berthold ob- 

 tained similar results. From studies of the 

 action of gymnema and other substances on 

 taste, Dr. Shore finds an explanation of it in 

 supposing that the nerve fibers or nerve endings 

 capable of being stimulated by pure sweet and 

 bitter substances are different from those which 

 are excited only by acid and salt. The selective 

 action of cocaine not only on the nerve centers 

 connected with taste, but on others associated 

 with more general sensory impressions, points 

 also to the multiplicity of the kinds of endings 

 of sensory nerves in the tongue. The more 

 powerful action of cocaine on bitter taste than 

 on sweet, and of gymnema on sweet taste than 

 on bitter, may also be an indication that the 

 nerve fibers or nerve endings concerned with 

 those tastes are also distinct. The selective 

 action of drugs between these two tastes is, how- 

 over, much less marked, and the constant group- 

 ing of these together gives some support to the 

 view that they may be due to different molecu- 

 lar activities of the same end organs. 



Examining the gustatory sensations excited in 

 12.") fungiform papillae, Ohnall has found that 21 

 per cent, are not sensitive at all. while 48 per 

 cent, are sensitive to sweet, bitter, and acid 

 tastes. Some are sensitive to only two, and a 

 few to sweet only, or to acid only, but no pa- 

 pilla was found which was sensitive to bitter 

 only. 



In a paper of contributions to the study of the 

 muscular sense before the American Neurologic- 

 al Association, Dr. G. F. Preston thought that it 

 illicit be considered definitely proved that the 

 muscular sense, or at least one part, is composed 

 of afferent impulses which are independent of 

 general sensibility. The next step that suggested 

 itself was the starting point of these afferent im- 

 pulses. Clearly, as several observers had noted, 

 the muscles alone that is, sensations coming 

 from them could not give us the information 

 we required as to the position of our limbs. Un- 

 doubtedly the tendons, the joints and their cov- 

 erings, and perhaps the bones, all aided in pro- 

 ducing the posture sense, or rather from these 

 proceeded nerve fibers conveying posture-sense 

 impressions. The loss or impairment of posture 

 sense was an almost constant symptom 'm scle- 

 rosis of the posterior columns of the cord. It 

 seemed probable that the fibers conveying pos- 

 ture-sense impressions passed into the retiform 

 body, thence to the cerebellum, and on to the 

 great brain. In 3 cases of tumor of the cerebel- 

 lum in'which necropsies had been made he had 



observed loss of posture sense without impair- 

 ment of general sensibility. 



Muscular System. A physical theory for the 

 explanation of muscle currents was propounded 

 in 1878, and matured in 1889, by M. D'Arsonvul, 

 who supposed them to be due to changes in sur- 

 face tension, occurring at the planes of separa- 

 tion of the bright and dim disks of the muscle 

 fiber; and he adduced several phenomena of 

 the currents that were explained by it. The 

 principal objections brought against it referred 

 to the absence of disks such as are spoken of in 

 the muscle fibers, and the failure of the theory 

 to explain nerve currents. The results of experi- 

 ments made by J. Herbert Parsons with a view 

 to testing the theory indicate that D'Arsonval is 

 correct in attributing such muscular currents to 

 a physical cause, although his explanation rested 

 on an erroneous anatomical basis. It would now, 

 pays the author, appear probable that muscle and 

 nerve currents are caused by the movements of 

 fluid in capillary tubes ; and since it has been in- 

 dicated by Prof. Burdon Sanderson that the 

 electrical change of contracting muscle does not 

 precede but actually coincides with the mechan- 

 ical effect, the hypothesis that the electrical 

 variation is produced by chemical changes which 

 precede the actual shortening is no longer neces- 

 sary. 



The physiological action of various pure or- 

 ganic nitrites of the paraffin series upon striated 

 muscular tissue has been studied by J. T. Cash 

 and W. R. Dunstan. When the vapors of these 

 nitrites came into contact with the muscle a 

 paralysing effect was observed. Several series 

 of concordant results were obtained, which lead 

 to two different orders of activity, viz., with 

 reference to the extent to which equal quantities 

 of nitrites shorten the resting muscle, and with 

 reference to the rapidity with which the shorten- 

 ing is produced. The order of activity of the 

 nitrites as regards the extent of the shortening 

 they induce is as follows: Iso-butyl, tertiary 

 amyl, secondary butyl, secondary propyl, propyl, 

 tertiary butyl, butyl, a amyl, amyl, ethyl, 

 methyl. The order representing the speed with 

 which shortening occurs is: Methyl, ethyl, sec- 

 ondary propyl, tertiary propyl, primary propyl, 

 tertiary nutyl, secondary butyl, a amyl, /3 amyl, 

 primary butyl, isobutyj. In very minute doses, 

 insufficient to cause passive contraction, these 

 nitrites interfere in a marked degree with tho 

 active contraction, and cause the muscle to fail 

 in responding to stimulation ; while the com- 

 panion muscle, contained in a closed chamber 

 free from nitrite vapor, still responded to stimu- 

 lation. The physiological action of these nitrites 

 did not appear to be solely, and in some cases 

 not even mainly, dependent on the amount of 

 nitroxyl they contained. In respect of all phases 

 of physiological activity, the secondary and ter- 

 tiary nitrites are more powerful than the corre- 

 sponding primary compounds. A large propor- 

 tion of an organic nitrite is changed into nitrate 

 in its passage through the organism, and is ex- 

 creted as an alkali nitrate in the urine. 



Kauffmann, experimenting on the masseter 

 and levator labii superioris muscles, has found 

 that the quantity of blood traversing a physio- 

 logically active muscle is enormously iiu 

 being in some instances as much as fivefold tho 



