tf ed THE MEDALS OF CREATION. Cuap. X. 
penetrates into all the single cells, the black rings of the air 
~  ag 
vesicles disappear, and the structure of the original is beau- — 
tifully displayed.* 
Sort PART OF ROTALLE IN CHALK.—The manner in which ~ 
T obtained the unmineralized soft bodies of foraminifera from — 
chalk has already been mentioned (ante, p. 360) ; but it may 
be useful to offer a few additional suggestions ; for such 
fossil remains are not easily extracted. Many experienced — 
microscopical observers have not succeeded in obtaining one 
good specimen ; but others have been more fortunate, or 
persevering. | 
In several glass test-tubes, (the more the greater chance 
of success,) put a few grains of chalk powder : pour the tube — 
half full of diluted hydrochloric (muriatic) acid—about ten 
parts water to one of acid—agitate, and set the mixture by: 
when all action has ceased add one or two drops of undiluted — 
acid to each tube, and repeat the process at due intervals 
till all the calcareous matter is dissolved. Pour off the fluid, 
substitute distilled water, agitate, and then let the sediment 
subside. The residue will consist of atoms of quartz and 
other insoluble mineral matter, and animal tissue, if there © 
be any. Then, with a camel-hair pencil, place a small por- 
tion of the sediment on a glass slide, and when dry cover it 
with Canada balsam, and treat it as above directed. Among 
a dozen slides thus mounted, there will probably be two or 
more good examples of the body, or detached membranous 
segments of Rotaliz or Textularie, like those figured in 
Lrgn. 118, 
CALCAREOUS SANDSTONES AND. Maris.—These substances 
may be examined by the same process; but if of loose 
texture, Dr. Bailey recommends that some of the sandy 
* Specimens of chalk, flint, and other rocks for examination; or 
specimens prepared on slides, may be obtained of the microscopic 
artists, named in the Appendix. 
