ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
893 
extraction apparatus which he has devised for dehydrating pieces of 
tissue (fig. 105). It consists of a flask capable of holding 25-30 oz. of 
fluid ; from the neck of the flask proceeds a tube through which spirit 
vapour at first, and afterwards liquid alcohol passes to a vessel in which 
the piece of tissue to be dehydrated is placed. From near the bottom of 
the flask proceeds another tube to the dehydrating vessel, and the latter 
is joined to the former by a siphon. Hence, if the flask be filled with 
alcohol above the level of the side tube and heated in the usual way, 
the pure spirit will pass along the upper tube to the siphon- vessel con- 
taining the tissue to be dehydrated, and then from this vessel back 
through the siphon to the flask. Hence this continuous distillation 
means rapid dehydration. The water is absorbed by putting a handful 
of quicklime in the flask with the spirit. 
The only other detail which may be mentioned is that from the 
middle of the lower or side tube which connects the flask with the 
siphon-vessel is a tube coming off at right angles. This seems to act 
chiefly as a safety valve. All the parts are connected with rubber tubing, 
and fixed in the usual way. 
Taken altogether, the apparatus seems to be very ingenious, and 
worth a trial, as its action is continuous and automatic, and the waste 
quite a minimum. 
Imbedding Vegetable Objects in Celloidin.* — According to Herr 
W. Busse it takes 3-4 weeks to properly prepare an object by the celloidin 
process. The object should be perfectly dehydrated and free from air, 
and be gradually impregnated with celloidin by successive immersion in 
solutions of increasing thickness. At least three different solutions are 
required. The next step is to imbed the object in thick solution in 
paper capsules. These are then plixced in alcohol for twenty-four 
hours, by which time the celloidin mass is ready for sectioning. The 
author deals with sectioning and the after treatment of the sections, and 
shows how to remove the colloidin by a modification of Chauveaud’s 
procedure. 
Paraffin Infiltration by Exhaustion. f — Mr. A. Pringle advocates 
the infiltration of tissues with paraffin by means of exhaustion on account 
of celerity ; certain and complete infiltration ; certain removal of the 
solvent ; absence of distortion of the tissue elements ; avoidance of 
overheating, and economy. 
The object may be fixed by immersing in saturated solution of HgCl 2 
for about 12 hours, and then washing in running water for a like 
time. After this it is passed through 30, 50, and 70 per cent, alcohols 
successively for 24 hours apiece. The pieces are preserved till 
wanted in 70 per cent, alcohol. Or the objects may be fixed and 
hardened in Muller’s fluid followed by the alcohols as above. When 
required the pieces are transferred from 70 per cent, alcohol to 
pure methylated spirit, and absolute alcohol (twice) each for 24 
hours. Chloroform is then pnt under the spirit by means of a 
pipette or syringe, and left for 24 hours. The mixture is replaced by 
* Zeitschr. f. Wiss. Mikr., viii. (1892) pp. 462-75. See Bot. Centralbl., li. (1892) 
p. 292. 
t Journ. Pathol, and Bacteriol., i. (1892) pp. 1 17-9. 
