762 



PHYSIOLOGY. 



in man as in other mammals that have been 

 examined ; it is also approximately the same as 

 the average rate of muscular response to rap- 

 idly recurring excitation of the nerve-centers 

 in animals. The average rate of muscular re- 

 sponse to volitional stimuli in man is approxi- 

 mately the same as that obtained both in man 

 and animals as the result of pathological or 

 other excitation of the cortex cerebri produc- 

 ing epilepsy, and it is nearly the same as the 

 rate of muscular response which is due to ac- 

 tivity of the spinal cord alone. 



From a study of the effect of muscular exer- 

 cise on the temperature of the body, M. Mosso 

 concludes that in therm ometrical relations the 

 nerves have much greater action than the mus- 

 cles. Strong emotion and pain will raise the 

 rectal temperature from 0'5 to 2. During a 

 walk of two days, the author observed that 

 his temperature was not in proportion to the 

 work done by his muscles. When dogs rest 

 after long fatigue, it is observed that their heat 

 sinks below the normal level, though their mus- 

 cular exertion has been great. Experiments 

 with strychnine and curare also go to confirm 

 the conclusion that internal temperature de- 

 pends chiefly on the nerve-centers and their 

 greater or less. excitation. 



Prof. Brown-Sequard has demonstrated that 

 for several weeks after death, or as long as 

 rigor mortis persists, the muscles of an animal 

 undergo slow alternate contractions and elon- 

 gations. The movements were only percepti- 

 ble when one or the other set of a group of 

 antagonistic muscles was divided, and they 

 ceased totally when cadaveric rigidity finally 

 passed away. The movements are absolutely 

 independent of external conditions of tempera- 

 ture, moisture, etc. In fact, in the same ani- 

 mal, while some of the rigid muscles are elon- 

 gating, others are contracting, and still others 

 are at rest. The author concludes that these 

 movements prove that the muscles in rigor mor- 

 tis are not dead, but are still endowed with 

 vital powers, while they are, however, in a 

 certain chemical condition which is antecedent 

 and preparatory to final death. 



Glandular System. Du Bois-Reymond in 1857 

 found the skin of the frog to be the seat of an 

 electromotive force of such a direction that 

 the outside of the skin was negative to the 

 inside; and further investigation showed that 

 the property was due to the glandular stratum. 

 Similar currents were discovered by subse- 

 quent observers in the stomach and intestines, 

 the mucous membrane of the throat, and the 

 tongue of the frog. The investigation of the 

 properties, and variations of this current has 

 been continued by W. M. Bayliss and J. Rose 

 Bradford. Concerning the " current of rest," 

 the results of previous observers were con- 

 firmed : the outside of the skin was invariably 

 negative to the inside, but the amount of poten- 

 tial difference varied considerably. The au- 

 thors were led to the opinion that this current, 

 in the case of the frog's skin as well as that of 



all animals, with cutaneous glands of any kind, 

 is partly due to the epidermis, but partly also to 

 the glands themselves; and thisopinion was con- 

 firmed by the results of the consecutive action 

 of corrosive sublimate and atropiu in the frog's 

 skin. Concerning the electrical changes that 

 occur in the glands of the skin on excitation of 

 the nerves supplying it, Engelmann asserted 

 that it was of the nature of a negative variation 

 of the current of rest, or that the mouths of 

 the glands became negative to the bases. Her- 

 mann, on the contrary, saw a positive varia- 

 tion, either alone or accompanied by a small 

 preceding negative variation, or u Vorschlag." 

 Experiments made in search of a reconciliation 

 of this discrepancy showed that the character 

 of the variation was different at different sea- 

 sons. Observations during January confirmed 

 Hermann's observations ; but as the breeding- 

 season approached, pure negative variations 

 became more frequent, and it was at last ex- 

 tremely rare to find a positive variation eitlier 

 alone or with a negative "Vorschlag." After 

 March, the positive variation began to reap- 

 pear, gradually becoming more frequent, until 

 ultimately it became the usual variation again. 

 During the last three months of the year, there 

 was a third phase to the variation, of a nega- 

 tive sign, but very slow as compared with the 

 other two. The excitating change, therefore, 

 when complete, consists of three phases. Sev- 

 eral hypotheses have been proposed to account 

 for these phenomena ; among them is one by 

 Hermann, which, supposing that the current 

 of rest is due to the epidermis and that during 

 rest the glands give no electrical current ow- 

 ing to their closed spheroidal form, the epi- 

 dermic current becomes relatively much more 

 powerful. This hypothesis seems to be the 

 more acceptable one, but not completely so; 

 for the authors are loath to admit that negative 

 variations of the power that has been observed, 

 are the result merely of the preponderance of 

 the epidermic current over the glandular cur- 

 rent. 



J. Munk has carried on experiments during 

 two years to determine between Ludwig's fil- 

 tration theory and Heidenhain's secretion the- 

 ory, of the secretion of urine. According to 

 the former theory, the blood - pressure pre- 

 scribes the measure for the secretion ; accord- 

 ing to the second theory, the urine is secreted 

 from the secretory epithelial cells of the kid- 

 neys, and the quantity of matter secreted is 

 dependent on the rate of movement of the cir- 

 culation of the blood. The facts deduced from 

 the experiments involved the exclusion of the 

 possibility of a central influence being exer- 

 cised from the heart or from the nervous sys- 

 tem on the kidneys, and were therefore deemed 

 by the author arguments proving that the 

 urine is secreted by the renal epithelial cells. 



Prof. Eternod, of Geneva, has published an 

 account of regeneration of the spleen in the 

 fox, the interesting point of which is that four 

 months after the spleen had been entirely re- 



