424 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
A Method of Imbedding Delicate Objects in Celloidin.* — Mr. 
Frank S. Aby writes: — The object, properly fixed and hardened, is 
placed for twenty-four hours in a mixture of equal parts of alcohol and 
ether. It is transferred to a thin syrupy solution of celloidin, made by 
dissolving celloidin in a mixture of equal parts of alcohol and ether. 
After remaining in this solution for about twenty-four hours, the object 
is covered with a thicker solution of celloidin and is allowed to remain in 
the same for about twenty-four hours, when it is ready to imbed on cork. 
When ready to imbed the object, a small quantity of the celloidin 
solution is spread on clean glass (a slide will answer the purpose), and 
allowed to dry. Then another coat is applied and allowed to dry. 
This affords a firm celloidin bed upon which the object is placed and 
arranged, care being taken to place it in the desired position as quickly 
as possible, before the celloidin begins to harden. The whole is now 
covered with successive layers of the celloidin solution, until a firm 
support is built up for the object. When sufficiently dry, the celloidin 
is removed from the glass by means of a sharp knife, and if necessary, 
a pair of scissors is used to trim the bed to the proper size and form. 
It is now ready to imbed on cork. 
The top of a cork is coated with celloidin solution and allowed to 
dry. This is done to prevent air from rising from the cork and forming 
bubbles in the celloidin. The object, in its matrix of hardened celloidin, 
is placed in the desired position on the cork, and fastened to it with 
celloidin. After drying in the air until a layer is formed on the outer 
surface firm enough to retain the shape, the cork is dropped into 50 per 
cent, alcohol. Usually the object is ready to cut after remaining in the 
alcohol one hour. 
This method of preparing a bed of celloidin has been employed with 
very satisfactory results in obtaining sections of embryo chicks. Blasto- 
derms of the earlier periods of incubation have been successfully 
sectioned. By arranging the embryo on the bed of hardened celloidin, 
it has been possible to get large symmetrical sections of the blastoderm. 
Celloidin contracts during the drying process, but by exercise of due 
care in arranging the blastoderm, distortion may be avoided. 
This method of imbedding has given good results in studying Hydra , 
and the preparation of the celloidin bed may be resorted to in almost 
every case where delicate objects are to be sectioned. 
C4) Staining- and Injecting-. 
Vasale’s Modification of Weig'ert’s Method, f — Sig. G. Vasale says 
that Weigert’s method for staining central nervous tissue may be 
rendered less cumbrous by the following procedure, for which three 
solutions are necessary. (1) Haematoxylin 1 grm. dissolved in 100 grm. 
water by aid of heat. (2) Neutral acetate of copper, saturated filtered 
solution. (3) Borax 2 grm., ferridcyanide of potash 2 • 5 grm., dissolved 
in 300 grm. water. 
The sections taken from spirit are placed in solution 1 for three to 
five minutes, then for same length of time in solution 2, whereon they 
* Microscope, xi. (1891) pp. 58-9. 
t Rivista Speriment. Freniatria e Med. Legale, xv. (1889) pp. 102-5. See Zeitschr. 
f. Wiss. Mikr., vii. (1891) pp. 517-9. 
