558 



chiefly, and perhaps rather exclusively, on the study of the animal 

 structure. Of the encouragement and aid received from that ex- 

 cellent man, Miiller afterwards spoke in the most grateful terms, and 

 he declares that it was through the influence and example of Rudol- 

 phi that his scientific pursuits were afterwards turned so much to 

 comparative anatomy. 



Miiller returned to Bonn in 1824, and in October of the same year 

 began his career as an academical lecturer in that university. In 1826 

 he was made Professor Extraordinary. In the meantime, however, 

 the duties he imposed on himself as a teacher had been unusually 

 onerous, and to these was added unremitting employment in original 

 investigation, with all its concomitant labour and thought. Such over- 

 strained exertion brought on a state of bodily exhaustion and mental 

 depression, which in 1827 obliged him wholly to lay aside work for 

 a season, and to seek for health and recreation in a journey up the 

 Rhine, and through the south of Germany, in which he was accom- 

 panied by his newly-married wife. Returning with recruited health, 

 and resuming his duties in Bonn, he was in 1830 promoted to the 

 grade of Professor in Ordinary ; and in the spring of 1 833 he was called 

 to occupy the chair of Anatomy and Physiology in Berlin, which had 

 become vacant by the death of his friend and preceptor, Rudolphi. 



Of the works published by Miiller during his stay at Bonn, the 

 first in point of time was one " On the Comparative Physiology of 

 Vision," which appeared in 1826*. This was immediately followed 

 by a smaller essay "On the Phantasmal Phenomena of Vision f," a 

 class of phenomena which had greatly interested and attracted Miiller 

 when a boy, and in the contemplation of which, as he himself in- 

 forms us, he used to give free play to his fancy. The appearances, 

 thus become early familiar to him, he subjected in maturer years to 

 philosophical scrutiny, and the work in which they are described 

 and discussed forms properly the continuation of the larger treatise 

 on vision which preceded it. Of this treatise, the leading charac- 

 teristics are, according to the opinion of one well qualified to judge J, 

 the masterly application of anatomy, physiological experiment, phy- 



* " Zur vergleichenden Physiologic des Gesichtssinnes des Menschen und der 

 Thiere," &c. Leipzig. 1826. 



t " Ueber die phantastischen Gesichtserscheinungen," &c. Coblenz. 1826. 



I Professor Theod. L. W. Bischoff, of Munich, in his " Festrede tiber Johannes 

 Miiller." Miinchen. 1858. 



