444 BIOLOGY IN RELATION TO OTHER NATURAL SCIENCES. 



uot have been possible had not its author, besides being a trained phys- 

 icist, known how to do as good work in a small room in the upi)er tloor 

 of the old university building at Berlin as any which is now done in 

 his si)lendid laboratory. Had Ludwig not possessed mechanical apti- 

 tude, in addition to scieutitic knowledge, he would have been unable 

 to devise the apparatus by which he measured and recorded the varia- 

 tions of arterial pressure (1848), and verified the principles which 

 Young had laid down thirty years before as to the mechanics of the 

 circulation. Nor, lastly, could Ilelmholtz, had he not been a great 

 deal more than a mere physiologist, have made those measurements of 

 the time relations of muscular and nervous responses to stimulation, 

 which not only afford a solid foundation for all that has been done 

 since in the same direction, but lias served as models of physiological 

 experiment, and as evidence that perfect work was possible and was 

 done by capable men, even when there were no physiological labora- 

 tories. 



Each of these examples relates to work done within a year or two of 

 the middle of the century.* If it were possible to enter more fully on 

 the scientific history of the time, we should, J think, find the clearest 

 evidence, first, that the foundation was laid in anatomical discoveries, 

 in which it is gratifying to remember that English anatomists (Allen, 

 Thomson, Bowman, Goodsir, Sharpey) took considerable share; sec- 

 ondly, that progress was rendered possible by the rapid advances which, 

 during the previous decade, had been made in physics and chemistry, 

 and the participation of physiology in the general awakening of the 

 scientific spirit which these discoveries produced. I venture however 

 to think that notwithstanding the operation of these two causes, or 

 rather combinations of causes, the development of our science would 

 have been delayed had it not been for the exceptional endowments of 

 the four or five young experimenters whose names 1 have mentioned, 

 each of whom was capable of becoming a master in his own branch, and 

 of guiding the future progress of inquiry. 



Just as the affinities of an organism can be best learned from its 

 development, so the scope of a science may be most easily judged of 

 by the tendencies Avhich it exhibits in its origin. 1 wish now to com- 

 plete the sketch I have endeavored to give of the way in which physi- 

 ology entered on the career it has since followed for the last half 

 century, by a few words as to the influence exercised on general physi- 

 ological theory by the progress of research. We have seen that no 

 real advance was made until it became possible to investigate the phe- 

 nomena of life by methods which approached more or less closely to 

 those of the physicist, in exactitude. The methods of investigation 



* The " Untersucliuugen iiber thieriscIieElectricitiit" appeared in 1848; Liidwig's 

 resciirclies on the circulation, wbicfi included the first description of the " kymo- 

 graph" and served as the foundation of the " graphic method" in 1847; Ilelmholtz's 

 research on the jjropagation in motor nerves m 1851. 



