328 SCIENCE PROGRESS. 



that before him lay a path leading- toward something- prac- 

 tical with good prospect of success. Ludwig sketched an 

 extended plan and very often entrusted to his pupils the first 

 use of an apparatus which he had himself invented and con- 

 structed in view of questions yet to be solved. How much 

 of the actual work he and his able mechanician Salvenmoser 

 did themselves depended on the capability of the pupil. But 

 despite his plan already laid down according to certain lines, 

 and despite his gift of lucid foresight of the nexus of things 

 physiological, the result of the experiment alone was 

 guide for all further steps in the investigation. " The 

 best that we can say is what nature itself says to us ;" these 

 words, which his revered teacher said a few months ago to 

 the writer of this paper, were the precept he always followed, 

 a precept which seems a matter of course, and yet is 

 so often subject to the temptation of being neglected. 



Ludwig's scientific achievements in physiology must be 

 viewed as to their importance, firstly, for the introduction of 

 new methods ; secondly, for their shedding new light on 

 numerous of the most complex processes of the animal 

 machinery. Foremost must be placed the invention of the 

 graphic method. It is only fair to say that Thomas Young, 

 stamping with his remarkable genius each manifold 

 subject that he treated, had before Ludwig invented 

 this method. But it was through Ludwig's quite indepen- 

 dent reinvention that it became common property, not alone 

 of physiologists, but also of all other scientific men, of 

 physicists, astronomers, and others. When, in the year 

 1847, Ludwig studied the influence of the respiratory move- 

 ments on the circulation in the aortic system, he, for the 

 first time, placed in the open limb of the mercury mano- 

 meter connected with the artery a float provided with a 

 pen, and let this record the oscillations of the mercury on a 

 drum revolving with a constant velocity. This first re- 

 cording apparatus — the Ludwig Kymographion — is now a 

 standard apparatus, always applied to if we want to question 

 the throbbing heart, the beating pulse, the breathing breast, 

 and, indirectly, by their answers, the nervous system regu- 

 lating these wonderful vital actions. The value of this in- 



