78 THE GENETIC AND 



this, I declare to this day that it was of the greatest 

 service for the development of our acquaintance with 

 the formation of the connective-tissue ; as a guiding 

 hypothesis and as a provisional clue to our investi- 

 gations. Virchow, on the contrary, if he impartially 

 reflects on the part he took in the diffusion of this 

 misleading doctrine, must reproach himself severely 

 for it. For "we must draw a hard and fast line 

 between what we are to teach and what we are to 

 investigate. What we investigate are problems," but 

 " the problem ought not to be the subject of teach- 

 ing." That Virchow, in his course of instruction, 

 every day belied this, his present view of teaching, 

 that he every hour taught his disciples some un- 

 proved, theory and problematical hypothesis, every one 

 knows who, like myself, for years and with the deepest 

 interest, enjoyed his distinguished instruction. Still 

 the captivating charm of this instruction in spite of 

 the defective method of unprepared lectures lay pre- 

 cisely in this, that Virchow as a teacher constantly let 

 us, his pupils, enter into those problems with which 

 he himself at the moment was occupied ; that he pro- 

 pounded to us his personal hypothesis for the eluci- 

 dation of the given facts. And what really gifted 

 teacher who lives in his science would not do the same ? 

 Where is there, or where has there ever been, a great 

 master who in his teaching has confined himself to 



