278 HEKMANN VON HELMHOLTZ: 



Prussian Ministry of Instruction, and to lead to my 

 being called to Berlin as Briicke's successor, and 

 immediately thereupon to the University of Konigs- 

 berg. The Army medical authorities, with thank- 

 worthy liberality, very readily agreed to relieve me 

 from the obligation to further military service, and 

 thus made it possible for me to take up a scientific 

 position. 



In Konigsberg I had to lecture on general 

 jpathology and physiology. A university professor 

 undergoes a very valuable training in being compelled 

 to lecture every year, on the whole range of his science, 

 in such a manner that he convinces and satisfies the 

 intelligent among his hearers the leading men of 

 the next generation. This necessity yielded me, first 

 of all, two valuable results. 



For in preparing my course of lectures, I hit 

 directly on the possibility of the ophthalmoscope, and 

 then on the plan of measuring the rate of propagation 

 of excitation in the nerves. 



The ophthalmoscope is, perhaps, the most popular 

 of my scientific performances, but I have already 

 related to the oculists how luck really played a com- 

 paratively more important part than my own merit. 

 I had to explain to my hearers Briicke's theory of 

 ocular illumination. In this, Briicke was actually 

 within a hair's breadth of the invention of the ophthal- 



