" In an eel, in which the brain had been carefully removed, and the spinal marrow de stroyed, the stomach was violently crushed with a hammer. The heart, which previously beat vigorously sixty times in a minute, stopped suddenly and remained motionless for many seconds. It. then contracted ; after a long in terval it contracted again, and slowly and gra dually recovered an action of considerable fre quency and vigour." " A frog was made perfectly insensible by the application of laudanum or alcohol. Its respiration ceased. It did not move on the application of any irritant. The circulation in the web was carefully observed. When it had long continued in the same enfeebled state without change, the thigh was crushed. The circulation in the minute and capillary vessels ceased at once, and never returned. The sto mach was now crushed in the same manner. The heart ceased to beat for many seconds. Its beat then returned, but never regained its former force." In these experiments we have the sudden influence of shock and its gradual subsidence. The experiment is peculiarly interesting in many points of view :— 1. it is the only one on record of the effects of shock induced solely and exclusively through the medium of the ganglionic system ; 2. it exemplifies the. effect of shock or excessive stimulus on the heart, with its gradual though incomplete subsidence.
The connexion of the ganglionic system with the irritability of. the visceral muscles,—the
heart, the stomach, the intestines, &c. forms the subject of an experimental investigation, in which I am at this moment engaged, and the results of which I purpose to give under the head of vis nervosa and vis insita. It is pro bable that the ganglia are to the internal mus cular organs what the spinal marrow is to the muscles of the limbs, viz. the power of irritabi lity, &c. This inquiry is founded on a fact first ascertained by myself, that, in spring, we may, by portions at a time with considerable intervals, totally destroy the brain and spinal marrow in the frog, eel, &c. leaving the circula tion in the web or the fins and tail.* We have thus isolated the ganglionic from the rest of the nervous system, on which we may therefore proceed to experiment, watching the effect of various agents on the circulation and on the action of the heart, the stomach, the intestines.
We have thus passed in review in its anato mical, physiological, zoological, pathological, and those peculiar relations, the question of the irritability of the muscular fibre. It only remains for us to advert, once more, to the ex treme importance of this principle in physiology : all physiology is involved, indeed, in the topic of the nervous system and the vascular system, and the principle of irritability seems, with its various and appropriate stimuli, to be placed between those two.
( Marshall Hall.)