690 



PHYSIOLOGY. 



assigns these nerves a foremost, which in man 

 are entirely efferent, and a hindmost group of 

 nerves of a mixed character are built upon the 

 same plan as the spinal nerves, both with re- 

 spect to the structure, function, and distribu- 

 tion of their nerve-fibers, and as far as the 

 arrangement of the centers of origin of those 

 nerve-fibers in the central nervous system is 

 concerned ; and he thinks it probable that the 

 reason for the deviation of the cranial nerves 

 from the spinal-nerve type is bound up with 

 the changes which occurred at the time when 

 a large portion of the fibers of the foremost 

 group of cranial nerves lost their functional 

 activity. 



Dr. Marckwald has brought for ward evidence 

 to show that, although the respiratory centers 

 in the medulla oblongata are automatically 

 active, as well as excitable by reflex action, yet 

 the automatically active center can only liber- 

 ate respiratory spasms, but no regular rhythmic 

 respiratory movements. 



Dr. Gersung, of Vienna, has successfully per- 

 formed the novel operation of transplanting a 

 portion of the nerve of a rabbit to the thumb 

 of a patient, Prof. Von Fleischl. The trans- 

 planted nerve not only united with the human 

 nerve upon which it was ingrafted and per- 

 formed its functions normally, but the opera- 

 tion resulted in curing a tendency to neurom- 

 atous degeneration with which the original 

 thumb nerve had been affected. The case is 

 further interesting from the light which it casts 

 upon the existence of a practical identity be- 

 tween the nerves of different species of ani- 

 mals. 



A remarkable ca?e is described by Mr. Sutton 

 in which the divided ends of a median nerve 

 that had been severed ten weeks previously 

 were dissected out, revivified, and after five 

 days began to recover function. Mr. Barwell, 

 discussing Mr. Button's paper, mentioned a case 

 in which recovery of a function occurred when 

 the parts were brought together six months 

 after division. 



Special Senses. The experiments of Herr Ur- 

 banschitsch, of Vienna, on the reciprocal influ- 

 ence of organs of sense lead to the general 

 conclusion that any sense-excitation results in 

 an increase of the acuteness of other senses. 

 Thus, sensations of hearing sharpen the visual 

 perceptions. If colored plates are placed at 

 such a distance that one can hardly distinguish 

 the colors, and various sounds are then pro- 

 duced, the colors become generally more dis- 

 tinct the higher the sounds. Similarly, one 

 can, while a sound affects the ear, read words 

 which he could not read before. The ticking 

 of a watch is better heard when the eyes .ire 

 open than when they are closed. Red and 

 green increase the auditive perceptions, while 

 blue and yellow weaken them. Several musi- 

 cians, however, were agreed that red, green, 

 yellow, and blue caused an intensification of 

 sound of about one eighth, while violet had a 

 weakening effect. Taste, smell, and touch are 



under like laws. Light and red and green 

 colors increase their delicacy, while darkness, 

 blue, and yellow diminish it. Under the influ- 

 ence of red and green, taste extends from the 

 anterior border of the tongue to the whole 

 surface; on the other hand, a strengthening of 

 smell, taste, or touch, exalts the other sensitive 

 perceptions. The reciprocal influence of touch 

 and the sense of temperature is specially inter- 

 esting. If we tickle the skin with a hair, and 

 plunge the hand in hot water, the tickling 

 ceases ; but, if the hand be placed in cold wa- 

 ter and a part of the body is tickled, the tem- 

 perature is felt more vividly. 



From a purely physical point of view, Prof. 

 S. P. Langley has concluded that the time re- 

 quired for the distinct perception of an excess- 

 ively faint light is about half a second. A 

 relatively very long time is, however, needed 

 for the recovery of sensitiveness after expos- 

 ure to a bright light, and the time demanded 

 for this restoration of complete visual power 

 appears to be the greatest when the light to 

 be perceived is of a violet color. The visual 

 effect produced by any given constant amount 

 of energy varies enormously according to the 

 color of the light in question. It varies con- 

 siderably between eyes which may ordinarily 

 be called normal ones ; but, letting 1 repre- 

 sent the amount of energy required to make 

 us see light in the crimson of the spectrum 

 near A, the average will give the following 

 proportionate results for the wave - lengths 

 corresponding approximately to the six col- 

 ors: Violet, 1,600; blue, 62,000; green, 100,- 

 000; yellow, 28,000; orange, 14,000; red, 

 1,200. Since we can recognize color still 

 deeper than crimson, it appears that the same 

 amount of energy may produce at least 100,000 

 times the visual effect in one color of the 

 spectrum that it does in another. The abso- 

 lute measure of energy represented by the 

 sensation of crimson light is 0*000,000,000,000,3 

 horse-power. 



Dr. Kosnig has made some experiments for 

 testing Holmgren's statement that very small 

 colored dots can be seen only of one of the 

 primary colors of Young and Helinholtz's 

 theory red, green, or violet. The statement 

 was not confirmed when the necessary precau- 

 tions were taken, and it was found that small 

 dots of any color, even yellow and blue, were 

 perceived as possessing their own objective 

 color. This had also been observed by Iler- 

 ing. Isaacksen had, further, investigated the 

 power which the eye possesses of distinguish- 

 ing between minute dot-like lights which are so 

 small that their image on the retina only falls 

 on one cone, and found that it was as fully 

 developed as for the colors of large surfaces. 



The attention of anatomists was first di- 

 rected to the papilla foliata of mammals as an 

 organ of taste by Van Wyss in 1869-'70, and 

 Engelmann in 1872. The investigations have 

 been carried on by other observers as to 

 man, by Krause, Ajtai, and Lustig. Boulart 



