WORK OF THE PHYSIOLOGICAL STATION AT PARIS. 393 



register and measure this fugitive pheuomenoii, and for tbat puri)oseI 

 liad recourse to the tracing apparatus wliich occupies to-day an impor- 

 tant place in our laboratories. Thus M. Frau^ois-Franck, who continues 

 with so much talent my teaching at the College of France, makes much 

 use of the graphic method. Those of you who follow his work have 

 often seen him examine at the same time upon the same animal, seven 

 or eight different vital movements, registering them by tracings placed 

 one above the other so as to make apparent the reciprocal relations of 

 all the phenomena that occur during the course of an experiment. 



Fig. 1, PI. XLVI, taken from the beautiful memoir of M. Franck upon 

 the action of digitalin, is an exam])leof thesemultiple registrations. The 

 five tracings shown ui)on this plate are, from above downward, as fol- 

 lows: First, that of a mercurial manometer indicating the pressure of 

 the blood in the carotid artery; second, that of another manometer 

 showing the variation of pressure in the pulmonary artery; third, tbat 

 of a sphygmoscope giving the pulsations of the pulmonary arteryj 

 fourth, that of another giving the carotid pulse; fifth, the lower line, 

 giving, in seconds, the time occupied by the experiment. Eeference lines 

 traced upon this sheet show the effects produced at the same moment 

 in the four tracings by a stimulus that causes a tetanus of the heart. 

 A simi>le inspection of this figure teaches us all the variations that 

 tetanus of the heart produces in the general and in the imlmonarj'' 

 circulation with a precision that the most attentive observation could 

 not attain. 



In a special vrork' I have described most of the tracing instruments, 

 paying special attention to those which do not re(|uire preliminary 

 vivisections, but record the action of organs by their exterior manifes- 

 tations. We can thus, in both man and other animals, record the pul- 

 sations of the heart and arteries, the respiratory movements of the 

 thorax and of the abdomen, the phases in the displacement of respired 

 air, the contractions of the muscles, with the various degrees of force 

 which they develop, the variations of caliber occurring in small vessels, 

 etc. jModeru physiologists pay particular attention to perfecting and 

 multiplying these apparatus already so widely applied and of a much 

 greater range of application than ha<l at first appeared possible. 



In fact this apparatus not only records the phenomena for which it 

 was directly invented, but permits us to ascertain indirectly other fiicts. 

 Thus the myograph, invented at first for recording the movement 

 of muscles, makes known indirectly the velocity of the transmission of 

 force in the motor and sensitive nerves, in the columns of the spinal 

 cord, and even in the different layers of the cortex of the brain. 



For the nervous acts of organic life, such as the contraction and 

 relaxation of vessels, of which we do not even have any conscious 

 knowledge, physiologists also possess a veritable myograph in the 

 graphic apparatus that records the changes of volume of organs. 



'La M6tliode grapliiqiie: Paris, G. Masson, 1885. 



