114 



SCIENCE. 



[N. S. Vol. V. No. 107. 



ferent parts of the mechanism by which the 

 mammalian circulation is carried on, and the 

 functional connection of all of these by means of 

 the nervous system with all the other organs 

 of the body, often render difficult, sometimes 

 impossible, the drawing of reliable conclusions 

 as to the direct effect of any agency on the heart 

 itself from experiments on the whole organism. 

 Here, therefore, was especially a case for the 

 application of the physiological method of isola- 

 tion : the separation of a given organ from all 

 its functional, if not anatomical, connections ; 

 and keeping it alive, in spite of this separation, 

 by the artificial maintenance of the necessary 

 conditions of continued vital activity in the case 

 of warm-blooded animals — a suitable tempera- 

 ture and a sufficient and constant supply of 

 arterial blood. With an organ thus isolated the 

 determination of the direct influence upon it of 

 various factors can relatively easily be certainly 

 determined. 



The isolation of the mammalian heart, which 

 Carl Ludwig and Alexander Schmidt had found 

 impossible in 1868, was first accomplished by 

 Newell Martin in 1881. In order to secure 

 arterialization of the blood sustaining the nutri- 

 tion of the heart, the lungs, rhythmical infla- 

 tion of which was artificially kept up, were left 

 in functional connection with it. The remain- 

 ing organs of the body, deprived of their nor- 

 mal blood supply soon die, the heart, however, 

 continuing to beat in a perfectly normal manner 

 for so long as five hours and more, although 

 deprived of all influence of the central nervous 

 system. The pressure under which venous 

 blood flows into its right side can be varied by 

 changing the height of the reservoir containing 

 this, as can also be the pressure under which 

 the left ventricle empties itself by alterations in 

 the height of the outlet connected with it. 



With the aid of this method, modified in details 

 as circumstances required, various important 

 fundamental questions in the physiology of the 

 mammalian heart were attacked and solved in 

 the Baltimore laboratory. Most of the com- 

 munications describing the results of these re- 

 searches are contained in the present volume. 

 Prof Martin having been author or joint au- 

 thor of them. 



Their titles are: ' A New Method of Study- 



ing the Mammalian Heart ; ' ' The Influence 

 upon the Pulse Rate of Variations of Arterial 

 Pressure, of Veinous Pressure, and of Tempera- 

 ture ; ' ' Observations on the Direct Influence of 

 Variations of Arterial Pressure upon the Rate 

 of Beat of the Mammalian Heart ; ' ' The Direct 

 Influence of Gradual Variations Tempera- 

 ture upon the Rate o Beat of the Dog's 

 Heart' (this formed the Croonian Lecture of 

 the Royal Society for 1883); 'The Action of 

 Ethyl Alcohol upon the Dog's Heart ; ' ' Ex- 

 periments in Regard to the Supposed Suction 

 Pump Action of the Mammalian Heart,' and 

 'On the Temperature Limits of the Vitality 

 of the Mammalian Heart.' It is of distinct 

 historical importance that in this last inves- 

 tigation, in which E. C. Applegarth took part, 

 it was found possible to isolate the heart 

 and keep it alive independently of the lungs, 

 the blood being aerated simply by air bubbling 

 through it. The recent work of Langendorfi" in 

 Rostock on the isolation of the cat's heart with- 

 out the aid of the lungs was thus essentially 

 anticipated. 



The other original investigations described in 

 the volume are mostly concerned with the res- 

 piration. They include Martin's elaborate 

 research on of the respiratory movements of 

 the frog and their nervous mechanism, and 

 the study of ' The Influence of Stimulation 

 of the Mid-Brain upon the Respiratory Rhythm 

 of the Mammal,' in which W. D. Booker was 

 collaborator, the results obtained being later 

 confirmed by Christiani in Berlin. Martin's 

 valuable contribution to the question whether 

 the internal intercostal muscles are to be re- 

 garded as inspiratory or expiratory in function, 

 his decision being in favor of the latter alterna- 

 tive, is, of course, also given. 



Those of Newell Martin's public addresses 

 on more or less general subjects included in 

 this volume well deserved to be so. They are 

 all admirably written and are most stimulating 

 reading. Martin was a strenuous advocate of 

 the justifiability of vivisection, and in several 

 of his addresses made most powerful pleas for 

 it. A passage such as the following is perhaps 

 more worth quoting in America at the present 

 time than when it was first written : 



"It is not mere physical suffering that we 



