861 



I'HYSIoLor.Y. 



readily excitable at the end of the most severe 

 march as during complete rest A high external 

 temperature was found to exert the same influ- 

 mS*S a light load as the heaviest load did 

 I more mcuWat temperatures, and some del a i Is 

 of the experiment* were found to depend on m- 



Nerveis Hyst.-Prof. \Val.l.- v.-r. in an 

 teeoant of the most recent researches on the 

 formative structures of the nervous system, 

 lavs special stress on the following sUten 

 St inUre nervous system consists of single 

 elemrau. which may most conveniently be called 

 MiSjrssji. each of which is composed of a i.ene 

 crll and its processes. These processes a; 

 the one hand, protoplasmic d+ndrttr*. which rap- 

 idly become branched, and, on the other hand, 

 Htwffss or OTOIM. which give off collateral 

 branches, soon become medullated, and end in 

 fine branchings, as also do the collaterals. Each 

 nerve cell has only one axon. The dendrites 

 convey impulses to the cell ; the neurites or 

 axons convey impulses from the cell. All nerve 

 fibers, both dendrites and neurites, end freely in 

 fine branchings. Every physiological path of 

 conduction, whether from the periphery to the 

 central nervous system or vice versa, consists of 

 two or more neurons ; neverofone. Conduction 

 in the neurons is always longitudinal. Impulses 

 are transmitted from one neuron to the other 

 only by means of the free endings of the ter- 

 minal branches. 



Prom experiment in which section of all the 

 sensory roots of the nerves di-triimted to a limb 

 1 lowed by permanent motor paralysis, in 

 addition to the anaesthesia which might* be ex- 

 pected to occur. Dr. Mott and Prof. Sherrington , 

 conclude that the whole sensory path from pe- 

 riphery to cortex cerebri is in action during voj- 

 untary movement. Dr. Martian, on the other 

 hand, maintains that there are no motor, but 

 only sensory centers in the cortex cerebri, sen- 

 sory impressions and the activity of sensory cen- 

 ters being the real guides for volitional action, 

 and the true motor centers existing only in 

 the spinal cord. Dr ,.u-h has shown 



that toe posterior roots of the spinal nerves are 

 not exclusively sensory, but also contain motor 

 fibers, which are distributed to the visceral mus- 

 cles originally developed from the lateral plates 

 ' 



Motso has set forth that the brain is a scat of 

 active combustion, and that its temperature 

 rises still higher when it is stimulated to activ- 

 ity by direct excitation or by drugs. The ex- 

 periments of Leonard Hill and N. I >. Nabarro 

 do not bear out these conclusions, for r 

 pttnfrom them that when compared with the 

 tides the brain is not a seat of ax 

 *ion.nd it seems very improbable to them 

 -houid be perceptibly great- 



5-"*r r^iu of 1&^S?EZ 

 Mjaof motor impulses is the same in 

 r nerve and spinal cord. Thttbtohttt 

 n^rr impressions in th. 



/ .'-, 



"i 1 !? ?5" d ' !n the oord alone 



- - - that 



hat in the transference of the sensory 



impression from the terminals ..f the 



rd t.. the cell- ( .f it 



locomotor ataxy the speed is slow (i in bnth.hm 

 especial l> in the cord. 



inin- >h. 



Of Sympathetic "f referred pain has b. 

 forded by the combined iv-ult- of 

 ments of 'Sherrington and the more dm 



Searches Of Head relative to th. 

 connections U-twcen the sensory n 

 the internal organ- of the thorax and al> 

 and certain other s, , 

 skin. Kxamples of | ,1. h li^'ht 



thrown are that over the che-t \\ln-n lh> 

 vessels of the heart are occluded in 

 toris, pain between the shoulder blades i i 

 diseases, the radiating pam- attending n 

 sage of calculi along certain dm : 

 headaches and neuralgias connected with vari- 

 ous kinds of visceral irritation. In th 

 ics. with those ,,f Langley and An* 



certain areas of the skin surface have b 

 fined as invariably the seat of nferr. 

 when certain deep organs are di- a-e.|. 



In his application of the results i.htaii.- 

 Gaskell's observations on somatic and s; 

 in.- nerves to the study of the em 

 A. C. Wright takes as an example the pi 

 ena observed in a kitten confroir 

 strange dog, and shows that such an em. 

 stimulus would call forth in the kitten a i 

 series of reflex responses. First, t hr-u-h 

 voluntary visceral nerves; then the 

 untary muscles would be called into ,i 

 lastly, a reflex response would take place i 

 tain parts of the voluntary muscular B\ 

 The essential features to be recogni/. 

 in every emotional reaction an th. 

 of the emotion in a violent sei 

 condition of extreme neural ten-ion in ; 

 flex center, and an overflow of neural < 

 into different paths. This overflow take- 

 tir-t into channels associated with 

 tary muscle, and lastly into those ass- 

 with voluntary mu-cle. The phy-iolo^j. 



of the emotion is to be found not 



il reflex actions, but in the hiirh 

 ten-ion of the reflex center which 

 to those actions. In childhood x,.n-'ry -timuii 

 call forth in each case response- of both 

 untary and voluntary muscle, while with in- 

 creasing age the outflow of neural el 

 the re:' r I.e. -..me- m. TV and in- 



striked to paths associated with invol 

 muscle. As a result of SUch tran-forma' 

 get voluntary action with a purpose. 



f control of the refli 

 ' a necessity, since. if each animal 

 lUS Were to evoke a separate refl.-x n 



'ini/.ation which wa- endowed with 

 tiveness at all approaching that of the i 

 organization, life would be a i 

 voluntary movement." Yoluntar\ mu-. 

 act to the slitfhte-t stimuli, but invol 



i!ar actj..n- are called out onh 

 stimuli or by a -ummation of slighter 

 Hi^ r h neural ten-ion in the n-fl. 

 fore necessary for these- reaction- of invol . 

 muscles, and all -uch hiu'h neural ten-ioi, 

 t-nded with symptom- of ditn . The : 

 ing of the "generalized somatico-vis< erul re- 



