i 
Microscopy. bre 
MICROSCOPY.! 
STRUCTURE OF THE Human Sxin.—The following note refers to 
a method of isolating the epidermis of human and other embryos 
from the underlying dermis, and to the presence of a layer of 
cells, not previously described, which may be observed in the 
epidermis when so prepared, and which corresponds, I think, to 
the epitrichium of birds. The method is also convenient for the 
study of the development of hairs. 
It is well known to physicians that if the foetus dies and is 
retained, it is preserved for a considerable period without disinte- 
gration of the tissues in the amniotic fluid. In specimens thus 
Preserved it is often found that the epidermis is loosened so much 
that strips can be removed without tearin g off the underlying tissues, 
Ow as the amniotic fluid is little more than a salt solution, the 
facts just stated naturally suggest that a salt solution preserved 
from septic changes is sufficient to loosen the epidermis of the 
embryo. My experiments have satisfied me that a sojourn of several 
days in a 0.6 per cent solution of common salt, with 0.1 per cent 
thymol added to prevent putrefaction, is a simple and satisfactory 
>a grow in size; one a litttle larger is seen just to the left of - 
E numbered 2, one a good deal larger is shown at 3. Sections 
te that such clusters are on the under side of the epidermis and 
hair; here the 44 ra O 
“<i the axial portion of the papilla has formed the hair, B 
While the cortical portion has formed the follicle, f; the end of the — 
` Edited by Dr. C. O. WHITMAN, Mus. Comparative Zoölogy, Cambridge, Mur. : 
The illustrations are borrowed from a forthcoming work on human embryology. 
