ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
423 
Canada balsam was found unsuitable, but good results were obtained witli 
tbe following medium. Glycerin-gelatin is mixed with equal volumes 
of acetic acid and glycerin and warmed up until all the constituents 
have become thoroughly mixed. At a temperature of 12° R. the mass 
is fluid but below this it is necessary to warm it before using it. If the 
mass under the cover-glass be not quite firm it is advisable to ring the 
preparation round with some cement. 
Demonstrating the Structure of Rotten-stone.* — Herr F. Dreyer 
adopted the usual procedure for examining the structure of rotten-stone 
and the distribution of the Radiolaria, viz. grinding down to one flat 
surface, then fixing this with balsam to a slide and then grinding down 
the other side, followed by balsam and cover-glass. 
Isolation of the skeletons of the organisms was effected by the 
following ingenious device. A saturated solution of Glauber’s salts was 
heated in a test-tube and pieces of rotten-stone, dried in the air, dropped 
therein. By this means they were thoroughly saturated and as they 
cooled down the process of crystallization effectually pulverized them. 
If the siliceous skeletons only be desired the following procedure is 
more simple. Small pieces of rotten-stone are boiled for a short time 
in hydrochloric acid, the carbonate of lime is dissolved and the thus 
separated skeletons fall to the bottom as a fine meal. The material 
should be washed with water in a large glass vessel, stirred up and 
allowed to stand for one or two hours. The supernatant fluid is 
pipetted off and the washing repeated several times. Finally, the 
material is dried in the air. By tapping the watch-glass containing 
some of the material, the finer may be separated from the coarser par- 
ticles ; some of the former can be mounted in balsam. 
Collodion-method in Botany.! — Mr. M. B. Thomas advocates the use 
of collodion rather than of paraffin for infiltrating plant-tissues. The 
tissue to be treated is first dehydrated and hardened in alcohol. It is 
then placed in a 2 per cent, solution of collodion made by dissolving 
2 grm. of gun-cotton in 100 ccm. of equal parts of sulphuric ether and 
95 per cent, alcohol. In this solution it remains from 12-24 hours, 
and is then transferred to a 5 per cent, solution, where it again re- 
mains 12 hours. It is then laid on cork and covered, by means of a 
camel’s hair brush, with successive layers of collodion, until it is quite 
inclosed in the mass, allowing each coat to dry slightly before apply- 
ing the next. After a few hours the collodion will be firm enough to 
section. 
C3) Cutting’, including Imbedding and Microtomes. 
Imbedding and Sectioning Mature Seeds.!— Mr. W. W. Rowler 
gives some useful hints as to the best method of imbedding mature seeds 
in paraffin and preparing them for the microtome. The method de- 
scribed is that in use in the botanical laboratory of the Cornell 
University. 
* Jenaische Zeitschr. f. Naturwiss., xxiv. (1890) pp. 471-548 (6 pis.). See 
Zeitschr. f. Wiss. Mikr., vii. (1891) pp. 498-99. 
t Proc. Amer. Soc. Micr., 1890, pp. 123-7 (3 figs.). % T. c., pp. 113-5. 
