Obituary Notices. 
1237 
This work is the mine from which anatomists of the present 
"day have extracted the greater part of their knowledge of human 
development, and it is from it that they have borrowed the greater 
part of the embryological illustrations which are used in their 
text-books. 
It is difficult to realise the labour and patience required to 
-successfully carry out investigations into the development of 
man. Human embryos in the first month — and this is the 
important month — of development can only be obtained at rare 
intervals, and as often as not they come into the hands of the 
investigator in a condition unfit for proper research, and never 
in the condition in which the embryos of most of the lower animals 
can be secured. By the most assiduous search after specimens, 
.and by the elaborate measures undertaken for their preservation, 
Professor His was enabled to overcome these initial difficulties. 
But His did not content himself by publishing descriptions 
and drawings of the human embryo and its different organs : he 
likewise constructed models of the anatomy of the Embryo at 
different stages of its growth. These models are singularly beauti- 
ful. The early human embryo is an exceedingly minute object ; 
in the middle of the first month of development it measures little 
more than 2 mm. in length. The skill which Professor His 
exhibited in the reconstruction and magnification of these small 
embryos was little short of marvellous. Wherever anatomy is 
taught these models form a part of the laboratory equipment, and 
they have proved of the greatest service, not only to the teacher 
and pupil, but also to all those engaged in embryological research. 
If we might venture from so much material to select one result 
obtained by Professor His which at the present moment appears to 
possess a specially far-reaching significance, we would point to his 
investigations into the origin of nerve cells and the growth of 
nerve fibres. This research does not cover a great extent of 
ground, but even taken by itself it would be sufficient to establish 
the reputation of Professor His on a lasting and permanent basis. 
In the early brain and spinal cord the nerve cells assume shape 
and by a process of migration take up their several positions 
within the central nervous axis. At first there are no nerve- 
fibres, so the embryo at this stage has a brain and spinal cord, but 
