1'HYSIOLOGY. 



645 



dueing very violent effects on the first injection, 

 after which even larger amounts could be toler- 

 ated with comparatively light effect. Theeffects 

 of at ropine, strychnine, and curare as respiratory 

 .stimulants were studied. The first effect of atro- 

 |iine was enormously to excite the respiratory 

 function; this primary excitement was fol- 

 lowed, if the dose had not been very great, by a 

 distinct fall in the air movement, not sufficient, 

 however, to overcome the first rise, and the air 

 movements remained for a long time distinctly 

 above the norm. Atropine failed to increase 

 the respiratory movements of a dog under the 

 influence of opium; but this result is held for 

 further investigation. The antagonism between 

 the action of chloral and atropine was very 

 plain. The air movement in chloralized dogs 

 was increased 250 per cent, by the use of atro- 

 pine, and it was found possible in one experi- 

 ment by a reinjection of chloral to reduce for a 

 second time the air movement. As a whole, the 

 experiments with atropine, both in the normal 

 and the chloralized dog, showed that its salts 

 greatly increase the respiratory movement of 

 air, and led to the conclusion that it is a direct 

 and powerful stimulant. The injection with 

 strychnine produced an extraordinary increase 

 in the respiratory air movement, and it was 

 proved to be a true respiratory stinmlant. In a 

 single experiment an increase of 60 per cent, 

 produced by strychnine was almost completely 

 overcome by the injection of a solution of mor- 

 phine. Cocaine was found to act as a powerful 

 respiratory stimulant, the influence of which, 

 however, failed in the presence of an over- 

 whelming dose of a respiratory depressant. In 

 endeavoring to formulate from the experiments 

 a conclusion as to the comparative value of the 

 respiratory stimulants, an almost insuperable 

 difficulty appeared in the lack of uniformity of 

 result. Cocaine and strychnine have so much 

 similarity of action upon the nerve centers that 

 the use of one will probably increase the danger 

 that may have been incurred by the administra- 

 tion of large doses of the other. The relations 

 of at ropine to cocaine and strychnine, however, 

 are different, and it would seem that by the 

 combined use of atropine and strychnine, or of 

 atropine and cocaine, the advantages of what 

 Dr. Wood calls " cross action " may be obtained, 

 the two drugs touching and re-enforcing one an- 

 other in their influence upon the respiratory 

 functions, and spreading wide apart from each 

 other in their unwished-for and deleterious 

 actions. 



Prof. Loewy has described experiments on 

 respiration under reduced atmospheric pressure, 

 carried out in a confined space which admitted 

 of very rapid reductions of pressure (to half an 

 atmosphere), with constant composition of the 

 inclosed air. The amount of reduction which 

 was borne without ill effects differed in the case 

 of the three persons on whom the experiments 

 were made, in accordance with the magnitude of 

 their respiratory activities; the greater the lat- 

 ter, the greater was the reduced pressure which 

 could be withstood. For any one person it ap- 

 peared that a greater reduction could be borne 

 while fasting or during work than after a meal 

 or during repose. Both oxygen and carbon 

 dioxide were found to do away with the discom- 



fort resulting from over-rarefaction of the air. 

 Slightly reduced pn-ssi ire had no effect on respir- 

 atory interchange, while, if the reduction was 

 considerable, more carbon dioxide was expired, 

 notwithstanding the diminished supply of oxy- 

 gen. The reduced pressure of the latter gas was 

 found to act on the respiratory mechanism in 

 such a way as to lead to deeper and hence com- 

 pensatory respiratory movements. 



By introducing a manomeU-r tube into the 

 trachea in cases where tracheotomy had been 

 performed, Dr. Aron has been able to note the 

 in) rat radical pressure under various circum- 

 stances. He found that inspiration is frequently 

 divided into two portions, but that expiration 

 is always continuous. In quiet breathing the 

 manometer marked in inspiration from 2 - 08 

 millimetres to 6*65 millimetres of mercury ; 

 in expiration, from + 1'23 millimetres to +6'29 

 millimetres. In coughing, the inspiration pres- 

 sure was 6 millimetres, and the expiration 

 pressure as much as +46 millimetres. 



Circulation. Prof. Hoy and J. G. Adami 

 have spent several years in attempting to give 

 the study of the intact mammalian heart the 

 accuracy which has been attained in the study 

 of the heart of cold-blooded animals. In a paper 

 to the Eoyal Society they point out the ease 

 with which cardial tracings may be misinter- 

 preted if certain elements of the mechanics of 

 the heart be not constantly kept in mind. Thus, 

 if, when the chambers of the heart become ex- 

 panded, there is a lessening of the extent to 

 which at each systole the muscular fibers con- 

 tract, this does not mean that the contractile 

 force is weakened ; for with' increase in the con- 

 tents of the cavities of the heart there is in- 

 creased strain thrown upon the walls, and a 

 comparatively slight diminution in the circum- 

 ference of the expanded ventricle suffices to 

 expel the same amount of blood whose expul- 

 sion when the ventricle is but little expanded 

 is accompanied by a greater diminution in 

 circumference. Thus, in considering the action 

 of the vagus upon the heart, it was shown that 

 stimulation of this nerve does not cause loss of 

 ventricular force of contraction. Moderate 

 stimulation induces weakening or paralysis of 

 the auricles, accompanied by ventricular dilata- 

 tion. This dilatation is due to the increased 

 venous and intraventricular pressure accom- 

 panying the slowed rate of beat. And though 

 there is now lessened systolic contraction of the 

 ventricular wall, and also lessened output in a 

 given time, each individual contraction leads to 

 the expulsion of an increased quantity of blood. 

 The only direct action of the vagus upon the 

 ventricle, according to the authors, is a diminu- 

 tion of the excitability of the ventricular mus- 

 cle. Upon continued fairly strong vagus ex- 

 citation the auricular rhythm is weaKened or in- 

 hibited, and does not suffice to set up the nor- 

 mal "sinus," or post-auricular rhythm of the 

 ventricles; so for a time the ventricles usually 

 cease to beat, but soon the independent, idio- 

 ventricular rhythm manifests itself. The same 

 is to be seen when, after the methods of Wood- 

 bridge or Tigerstedt, the mammalian ventricles 

 and auricles are cut off from one another: or, 

 again, shows itself after musearin poisoning. 

 With a certain degree of vagus excitation, irreg- 



