702 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
agent under a cover-glass placed on glass rollers made of bits of capillary- 
tubing. This allows the use of bigb-power objectives, and tbe orienta- 
tion of tbe embryo in any desired position for a camera drawing. 
Methods of Investigating Sponges.* * * § — Mr. G. Bidder’s experiments 
on tbe alteration of cells during preservation for histological purposes 
showed him that tbe dangers of tbe imbedding process are modified by 
very gradual dialysis from alcohol into benzole, and largely guarded 
against by super-hardening in 1 per cent, osmic acid, and in absolute 
alcohol. For osmic acid even sponge tissue requires to be cut into 
the smallest practicable pieces, and repeatedly shaken, or the inner 
chambers will not be thoroughly hardened. Dialysis from water into 
absolute alcohol, or from alcohol into benzole, each took from 6 to 12 
hours. Mr. Bidder’s best preparation was stained in bulk with equal 
parts of Grenacher’s haematoxylin and 70 per cent, alcohol, being brought 
into this solution from 40 per cent, alcohol by four equal changes of 
strength. No acid was used, and the result was a very valuable over- 
staining of the collars and iris membranes. It will be found convenient 
to have in a pipette a thin solution of balsam in chloroform, so that it 
can be squirted instantly on the sections after removal from the chloro- 
form, to prevent drying before the thicker balsam has time to spread. 
Study of Paramaecium.j’ — Mr. Ryder found that osmic acid and 
corrosive sublimate gave good results in killing and fixing his material, 
as both reagents act with such rapidity as to exclude in a large measure 
the production of artifacts. Staining was done on the slide with hsema- 
toxylin and Biondi’s (= Heidenhain’s) mixture. Very good results were 
also to be got by staining objects in toio. 
(3) Cutting-, including Imbedding and Microtomes. 
Strasser’s Ribbon Microtome-t — Prof. H. Strasser gives detailed in- 
structions for mounting and preserving the serial sections prepared by 
his so-called “ Schnitt-Aufklebe ” Microtome.§ For sticking the sec- 
tions on the paper band the author uses the following mixture : — Gum 
arabic 80 to 100 ; water 100 ; glycerin 10 ; with the addition of a little 
carbolic acid. The paraffin sections gummed on the paper with the 
solution can be numbered and kept for months and years unchanged, 
until opportunities for their further treatment, colouring, &c., may 
arise 
The staining of the serial sections involves the following opera- 
tions : — 
A. Transformation of the paraffin section into a celloidin section. 
(1) Xylol bath, 1 hour. (2) Bath of 95 per cent, alcohol, 4 to 1 hour. 
(3) Collodionising. 
B. Staining. (4) Colouring solution (haematoxylin acidified with 
acetic acid). (5) Bath of Muller’s liquid, 5 to 10 minutes, wash in 
water. (6) Bath of permanganate of potash (1 in 600 water), 5 minutes, 
wash in water. (7) Bath of differentiating liquid (potassium sulphide 
* Qunrt. Journ. Micr. Sci., xxxviii. (1895) pp. 38 and 9. 
t Proc. Acad. Nat. Sci. Philad., 1895, p. 170. 
% Zeitschr. f. wiss. Mikr., xii. (1895) pp. 154-68. 
§ See this Journal, 1891, p. 281 ; 1892, p. 703. 
