330 SCIENCE PROGRESS. 



for physiological method, could describe this, the youngest 

 Physiological Institute in Kurope, an offspring of his great 

 master. 



In the last century Albrecht von Haller had formed and, 

 in a certain sense, proved his celebrated doctrine of irrita- 

 bility. It was reserved for Ludwig to shed full light on the 

 deep importance of this principle, and make it available for 

 scientific research by introducing his second <jreat method 

 into physiology. He perfused with blood the organs of the 

 dead animal under the conditions appropriate to each, and 

 awakened in this manner the seeming dead to new life. The 

 excised muscle, heart, lung, kidney, testicle, liver, and the 

 walls of the blood-vessels performed vital processes, the 

 course of which was only subject to the variable conditions 

 of the experimenter. And as evidence of these inner pro- 

 cesses, the chemical examination of the perfused blood re- 

 vealed the interchanges of gases and matter which had 

 taken place between the tissue and the blood, the chemical 

 composition of which had been previously regulated ac- 

 cording to the purposes of the investigation. The success 

 of this method not alone proved decisively that each tissue 

 had its own irritability, but it also showed that the entity, 

 which we call life, is composed of a whole set of lives in 

 great extent independent of each other ; hereby was opened 

 a new view for the co-ordination of the organism. The ana- 

 lytic method, that most proper to all exact scientific research, 

 was hereby not exactly introduced into biology, but gained 

 its characteristic physiological form. The elementary func- 

 tions of, for instance, nerve and muscle had been investigated 

 by good methods, and in certain sections of physiology a 

 clearness of description had been developed which could vie 

 with that of physics. But in these investigations a complex 

 of external purely physical and internal semi-vital phenomena 

 had been made to interact so that it remains an open ques- 

 tion as to where in the results the line between vital and not 

 vital process should be set. With Ludwig's new method, 

 it was quite different. Here the experimenter simply tried 

 to offer to the isolated organ, as far as possible, the con- 

 ditions that surround it in the body, and all the results were 



