THE AMERICAN 
MONTHLY 
MICROSCOPICAL JOURNAL. 
Wor, VIL. SEPTEMBER, 1887. No. 9. 
On methods of preparing tissues for microscopical study and brains 
for anatomical demonstration.* 
By J. W. BLACKBURN, 
OF WASHINGTON, D. Cc. a 
FREEZING METHOD. 
Undoubtedly freezing, if properly done, gives us the best method of demon- 
strating what we conceive to be the true condition of the tissues immediately 
after the cessation of life. The histological elements are fixed in their true 
shapes, sizes, and relative positions. It is, however, impossible to prepare 
tissues for the microscope without some manipulation, and the freezing and 
thawing and the subsequent staining, if the sections be stained before exam- 
ination, may produce unsatisfactory results. 
It is probable that with the ether-spray freezing apparatus the action of cold 
upon the tissues is more easily applied and controlled and less injury done to 
the tissues than by any other method of freezing ; and if the sections cut by 
this method be examined in glycerin, unstained, or, if stained, using only the 
aqueous reagents, we believe we may claim a minimum of alteration for the 
freezing process. 
The ether spray apparatus I exhibit is the one used with the Schanze mi- 
crotome. It works very well, is simple, portable, inexpensive, and the rub- 
ber parts easily replaced if they become rotten, as they will in time. On the 
metal plate it is easy to freeze + inch of tissue in a short time with the evapo- 
ration of a small amount of ether; and from this thickness of tissue a large 
number of thin sections may be cut. 
The tissue should be frozen to about the consistence of hard cheese; if 
harder, the knife will jum or the edge will be spoiled. 
It is advisable to use the best anesthetic ether, as the commercial article 
will not spray well, and the difference in the expense is slight. 
Tissues may be cut perfectly fresh or after partial hardening. If used fresh 
they are placed for a few minutes in a thick solution of gum arabic or gum and 
syrup ; but even this is not necessary, and is only used to assist in freezing the 
piece to the metal plate. 
If hardened first in any of the watery solutions the same method will an- 
swer, but if alcohol has been used the pieces must be placed in water for 
about 12 hours to remove the alcohol before placing in the gum. After 
hardening, however, the method can no longer be considered preferable to 
the interstitial imbedding processes to be described later. 
The sections must be cut on some form of microtome, and the knife should 
be kept cold and dry and at nearly a right angle to the line of its motion. 
* Read before the Washington Microscopical Society on May 24th, 1887. 
