384 THE HISTORY OF BIOLOGY 



find here, for instance, a number of statements quite in the spirit of Goethe's 

 speculations. The experimental method is scornfully rejected — Magendie's 

 experiments in particular are the object of adverse criticism — and the 

 search for "divine life in nature" is highly commended. The function of 

 physiology is said to be to comprehend the phenomena of life, not from the 

 point of view of experience, but from that of the idea of life. This again is a 

 proof that a keen observer can create fresh values in spite of a weak theoreti- 

 cal standpoint. Miiller's propensity for observing the life-manifestation of 

 his own senses was really unique, but the danger that always attends such 

 self-introspection threatened him no less; his nervous system was shattered 

 by his "fantastic sense-observations" and he fell into a state of melancholy 

 bordering on insanity. Rest and careful tending restored him, it is true, but 

 he gave up for ever these "subjective" researches and therewith also most of 

 the natural philosophy upon which they were based. We may say that this 

 mental disease involved the downfall of natural philosophy in Germany. 



J. Mulle/s experiments on sensory and ?notor nerves 

 MiJLLER, indeed, never abandoned his idealistic view of life, but his natural 

 research was now based on the principles laid down by Rudolphi — a 

 comparative study of the phenomena of life based on the knowledge of their 

 organs in different animal forms. He thus took up for renewed investigation 

 the Bell-Magendie experiments on the sensory and motor nerve-roots and he 

 succeeded in finding a more suitable subject for investigation than his pre- 

 decessors; they had experimented on dogs and rabbits, while Miiller had re- 

 course to frogs, which are of a more enduring nature and can therefore lend 

 themselves to more careful observation. Miiller in fact essentially widened 

 the knowledge of these important phenomena. His reinvestigations have 

 thrown a special light on reflex movements. Another field of study that par- 

 ticularly interested him was the embryonic development of the sexual or- 

 gans, in which he considerably widened the field discovered by Rathke and 

 von Baer; he also threw considerable light on the knowledge of the evolu- 

 tion of the mesonephros or middle kidney. Further, he made important 

 observations in regard to the glandular systems of the higher animals; in 

 particular, he definitely determined the glands' character of closed tubes 

 without connexion with the blood-vessels. He embodied the whole of his 

 knowledge on this subject in his Handbucb der Physiologie des Menschen, the 

 work which contains the clearest exposition of his general biological views 

 and which became the authoritative source of the contemporary conception 

 of life-phenomena, which held good up to the advent of Darwinism. 



Miiller introduces his physiology with some general observations on 

 the essence of life, which show how deep was the influence that natural 

 philosophy still had on him, even after he had broken away from it. He is a 

 vitalist, and a much more positive one than Bichat, for instance, who really 



