1895.] Microscopy. 85 
Single organs or pieces of muscle are quickly hardened in formol. 
It is notable, as pointed out by my son,‘ that the coloring matter of 
the blogd is distinctly retained. The blood courses, it is true, fade and 
finally to all appearances disappear, but if the preparation be placed 
in alcohol of not too great a strength (60-90 per cent.)—the stronger 
the quicker the reaction—the characteristic blood color returns and 
there is obtained an excellent representation of the branching of the ves- 
sels. The change from formol to alcohol and vice versa may be repeated 
always the same results. 
Brain hardened in formol gives very fine results.’ Pieces and even the 
entire brain are hardened very quickly and show the white and gray 
matter sharply differentiated from one another. Sections are said to 
be much better than those of chromic acid preparations. 
As has been mentioned, neither the microscopic structure nor the 
staining properties of tissuesare destroyed by formol. Almost all the 
organs and staining methods have been tried. In the preparations, 
cell body and cell structure, as well as the nucleus caught both in the 
resting state and in process of division are fixed, while the blood sio 
cles are sharply marked off from their surroundings. 
Hens’ eggs have been tried and have in many ways led to very 
interesting results. An unbroken fresh egg in a 1:15 solution showed, 
after 8 days, the white forming about the yolk a mantle of an outer 
fluid and an inner slimy consistance. The yolk was hard, remaining fluid 
only in the middle. The hardening process here then is the reverse of 
that of cooking. On the day following, the yolk had become much hard- 
er, while the white was changed only after a long time and never neared 
the hardness of the yolk. Upon opening an egg after 38 days a faint 
odor of formol was perceived. The yolk was hard, sectionable, and 
showed an outer zone of 14 mm. breadth and an inner beautiful yel- 
low mass. The yolk was surrounded by a grayish, scarcely sectionable, 
gelatinous mantle in which the chalazea and germinal-spot were plainly 
visible. About the mantle was a very slightly opalescent albuminous 
fluid. 
A fresh egg with a small hole in it showed under like conditions the 
same phenomena, but within a shorter time, or about 17 days. After 
68 days such an egg was noticeably harder., The firm white clung to 
* Anatomischer Anzeiger, m = No. 7. 
5 See Born, D r Anzahl in F idehyd (Form Tirehirtatar 
menschlicher Gehirne.” Meas Sektion d. schlesisch. Gesell. £ vaterl. Kultur. A 
1894. 
