PHYSIOLOGY. 



563 



functional performances were the true criteria for 

 nerve-fibers. Among recent,observers, Howell and 

 Huber, who had used both histological and experi- 

 mental methods, had arrived at the conclusion that 

 the axis-cylinder, the essential portion of a nerve- 

 fiber, had an exclusive central origin; they ad- 

 mitted that the peripheral tissues in which it was 

 embedded were active in preparing and generating 

 a nutritive scaffolding for it. The authors had 

 obtained experimental results which, so far as they 

 at present went, confirmed these views. 



The truth of the view, which has long been gen- 

 erally held, that repeated or excessive activity 

 caused fatigue of nerve-endings, but had no effect 

 upon the fibers that conduct the nervous impulses, 

 has been questioned by Herzen, who asserted that 

 after a nerve-trunk had been subjected to repeated 

 stimuli the subsequent response of the nerve 

 showed signs of impairment when examined by 

 electric tests. Observations of this impairment 

 made by Prof. Gotch have shown that it was a 

 change confined in its situation to the neighbor- 

 hood of the place of the electrodes by which the 

 electric currents used for fatiguing the nerve 

 were applied to it. Were the effect a true fatigue 

 effect, its locus should not be confined to the elec- 

 trode region, but should be distributed throughout 

 the nerve; because the process of conduction of 

 nerve-impulses occupying the whole length of the 

 nerve, the true fatigue which arose as their after- 

 effects must have a similar distribution. The 

 changes which were confined to the immediate 

 neighborhood of the electrodes by which the long 

 series of fatigue-producing currents were in- 

 troduced, were those to which much attention has 

 long been devoted as electrotome. Probably the 

 process involved was one of electrolysis, and cer- 

 tainly its relation to fatigue in the true sense was 

 at most extremely remote. 



T. Grigor Brodie and W. D. Halliburton, hav- 

 ing observed that the assertion that the nerve 

 fibers are incapable of fatigue rests on the excita- 

 tion for long periods of time of medullated fibers, 

 determined to repeat the experiments, with some 

 modification, on non-medullated fibers. Selecting 

 the nerves leading to the spleen, they found that 

 even after many hours of stimulation no evidence 

 of fatigue could be demonstrated. Nevertheless, 

 they obtained proof that certain non-medullated 

 as well as medullated fibers are injuriously af- 

 fected by prolonged faradic stimulation, and that 

 the spot which has been excited is no longer exci- 

 tabje until a considerable period of rest has 

 elapsed. 



Prof. C. S. Sherrington and Dr. A. S. Grunbaum, 

 describing before the British Medical Association 

 the experiments they had made upon the motor 

 cortex in anthropoid apes (13 chimpanzees, 2 

 orangs, and 1 gorilla), mentioned as a most im- 

 portant point brought to light in their researches 

 that the excitable motor region, though extending 

 deeply into the Rolandic or central sulcus, did 

 not extend on to the free surface of the post-cen- 

 tral convolution an observation that was in op- 

 position to the results of previous observers. The 

 authors gave the movements obtained from their 

 different areas broadly as follow: In the face 

 area eye, eyelid, nose, jaw, vocal cords, mastica- 

 tion, and also movements of the mouth and 

 tongue; in the arm area shoulders, elbow, 

 wrist, fingers, and thumb; in the leg area 

 toes, ankles, knee, hip; in each case from above 

 downward. Movement of the arms was obtained 

 by stimulation just at the border between the ex- 

 ternal and mesial surfaces of .the hemisphere. A 

 further difference from the result of other ob- 

 servers on the anthropoids was the case with 



which epileptiform convulsions were obtained 

 from the cortex. The authors had first studied 

 the results of ablation of parts of the cortex and 

 found that marked paralysis occurred from even 

 a small lesion, but that this was recovered from; 

 and they had also observed almost complete re- 

 covery after double extirpation of the arm area. 

 Prof. Sherrington had also investigated the direct 

 pyramidal tract in the anthropoids, and found 

 that in the chimpanzee a vertical pyramidal tract 

 occurred as in man, and was also, as in man, of 

 a very variable individual character. 



The paper of Prof. Sherrington and Dr. Grun- 

 baum was followed by an account by Dr. Campbell 

 of his studies of the histological features of the 

 cortex of anthropoid apes. The author enumer- 

 ated as special characters which he had found in 

 the motor region: 1. The possession of a well- 

 marked zone or tangential field. 2. A supraradia- 

 ting field. 3. A radiary zone of great depth and 

 richness in nerve-fibers, or of great " fiber 

 wealth " ; further, there were large ganglion-cells 

 or cells of Betz in this region. These histological 

 results were in complete accord with the experi- 

 mental results of Sherrington and Grunbaum, as 

 the motor type of structure was bounded poste- 

 riorly by the fissure of Rolando and did not extend 

 into the post-central convolution. 



The importance of cholin in blood in cases of 

 nerve degeneration, not only in such diseases as 

 general paralysis, but in various diseases of the 

 central and peripheral nervous system, is shown 

 by Dr. T. W. Mott and Dr. W. D. Halliburton in 

 an article on The Chemistry of Nerve Degenera- 

 tion. The detection of cholin, which is a prod- 

 uct of the decomposition of lecithin, is effected by 

 a chemical test the obtaining of the yellow octa- 

 hedral crystals from the blood; and also by a 

 physiological test, viz., a temporary fall of pres- 

 sure when it is injected intravenously in animals. 

 Degenerate nerves of animals were examined by 

 the Marche reaction, which consists of a mixture 

 of osmic acid and Miller's fluid, by which degen- 

 erate nerve-tissues are stained an intense black, 

 while healthy fibers are not stained. 



Almost all the experimental evidence with re- 

 gard to the localization of cortical centers has 

 been obtained from observations on monkeys 

 and lower animals; and except for the work of 

 Beevor and Horsley upon the orang-utan no 

 observations have been made on anthropoids. 

 Sherrington and Grunbaum, however, as a result 

 of some more extensive work on the same subject, 

 have recently in part confirmed and in part modi- 

 fied our previous knowledge. 



The presence of a facial reflex, sometimes 

 known as the extraorbital reflex, has of late at- 

 tracted considerable attention. The manifesta- 

 tion is produced by striking some part of the 

 forehead, and is followed by contraction of the 

 orbicularis, with more or less movement of the 

 eyelids. It is generally found that on tapping 

 the frontal region contraction of the orbicularis 

 takes place on both sides. The path for the re- 

 flex passes centripetally through the fibers of the 

 supraorbital nerve to the sensory nucleus of the 

 fifth nerve, and thence to the nucleus of the 

 upper branches of the seventh nerve on both 

 sides. Macarthy, in the Neurologisch.es Central- 

 blatt, says that he found the reflex present in 

 100 normal persons investigated. Further obser- 

 vation is required to decide whether this is a 

 true' reflex or not, and also to show what signifi- 

 cance may be drawn from its presence or absence. 

 Dr. Walker Overend has called attention to the 

 fact that he had previously described this reflex in 

 the Lancet of March 7, 1896. 



