Late Editor Guy’s Hosp. Reps.; Author of “Sleeping and Dreaming,” an Essay on Physiological Science; “The Physiology of Sleep,” etc.
“… It occurred to me that the artificial exposure of the brains of living animals might afford opportunity for more definite observation and further inquiry. With this idea I made numerous experiments and observations.… It was suggested to me that the perforation of the skull placed its contents in an unusual condition with regard to atmospheric pressure, and that thus an unnatural state of the circulation might be induced.… To obviate this and other possible objections, I replaced the portions of bone removed by accurately fitting watch glasses, and rendered the junction of their edges with the bone air-tight, by means of inspissated Canada balsam.… I satisfied myself of the accuracy of these observations by repeated experiments upon different animals. My experiments upon dogs were the most satisfactory; those upon rabbits least so.”—From “Physiology of Sleep” Guy’s Hospital Reports, Vol. VI., 1860, p. 153, &c.
“The method employed by Donders and Ehrmann was the same as that employed by Durham in the experiments he made upon animals to verify the observations of Blumenbach, Caldwell, and others, on human patients.”… “The results obtained by physiological experimentation, to prove that sleep is accompanied by cerebral congestion, according to some, and according to others by cerebral anemia, are not more valuable than the results of clinical observation. Firstly, the animals upon which the experiments have been made have been wounded more or less severely, and thereby both excitement and pain have been caused; all have, therefore, necessarily been placed under pathological conditions. It is impossible to wound the head and open the skull without causing a severe shock to the system of the animals, and a more or less violent irritation of the brain; that is to say, not without producing a certain amount of pain. And we know the influence that pain can have, not only on the functions of the great organic apparatus (circulation, respiration, animal heat), but also on the anatomical and physiological state of the nerve centres. Another influence which, according to our idea, very considerably diminishes the value of the results of physiological investigation, is that sleep has always been produced by narcotics and anæsthetics in the animals submitted to experimental observations.”… “We conclude from this study that the real state of cerebral circulation, during natural sleep, does not seem to have been arrived at, notwithstanding the great number of observations and experiments lately made on this interesting subject.”—Dr. Marvaud, Gazette Médicale de Paris, 1878 (p. 81-2).
Eckhard, C. M.D. Prof. Univ., Giessen.
Author of “Beiträge zur Anatomie und Physiologie,” Giessen; “Die Bildung und Prüfung des Arztes;” “Experimental physiologie des Nervensystems;” “Lehrbuch der Anatomie des Menschen.”
“It is known that there is no unity of opinion amongst the observers of the phenomena which occur during artificial respiration in animals poisoned by strychnine, and that furthermore those who agree about the facts insist upon giving these different meanings.”—“Ueber den Strychnintetanus während der Künstlichen Respiration,” “Beiträge,” p. 37.
“Expansion of the walls of the chest and abdomen by injection of gas into the lungs. First I cut away so much of the larynx through the open mouth of a frog that the animal can no longer close it at will. Then I sew the under jaw firmly to the upper jaw. I stop up the one nostril by forcing into it a short thick piece of wire. Then a similarly short and thick canula which is in communication with the gasometer is fixed into the other nostril. As soon as the frog shows symptoms of strychnine cramps, its lungs are set in communication with the gasometer by opening the tap; a side offshoot of the tube leads to the hdrg. manometer.”—“Strychnine, &c.” p. 48.
Eichhorst, Hermann. M.D.; Prof. Clin. Med., Univ. of Göttingen.
Author of “Handbuch der speciellen Pathologie und Therapie für practishe Aertzte und Studirende;” “Die trophischen Beziehungen der Nervi vagi zum Herzmuskel,” in Centralbl. f. d. Med. Wiss., 1879; “Lehrbuch der Physikalischen Untersuchungs-Methoden innerer Krankheiten,” Brunswick, 1881; “Ueber Nervendegeneration und Nervenregeneration,” Archiv. für path. Anat., Vol. LIX., 1874, p. 7.