Abstract
Feti of man, rabbit and mouse can be silver-impregnated in such a way that different kinds of nerve-fiber pathways in the peripheral nervous system are distinguishable from one another by different degrees of impregnation intensity. In the application of Bielschowsky's technic, it is important that the impregnation time in silver nitrate should be tested with respect to the species in question. This time is for man 6 weeks, for rabbit 3 weeks and for mouse 2–3 days.