ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
403 
sucli specimens may be afterwards stained with carmine, &c., sectioned, 
and mounted in balsam in the usual manner, and give perfect satis- 
faction, even after a stay of two years or more in the glycerin.” 
Experimental Imitation of Protoplasm."^ — Prof. 0. Biitschli has 
communicated to Prof. Eay Lankester a full account of the methods by 
which he attempts to imitate protoplasm. f A medium-sized watch-glass 
or flat dish must be filled with a thin layer of common olive oil and be 
placed on a water-bath or small cupboard at a temperature of about 
50° C. The great point is to select the right moment at which the oil 
attains the proper degree of thickness and viscosity ; this moment can, 
how’ever, only be found by systematic trials. After three or four days a 
trial may be made. Should the drop not have become finely vesiculate 
and exhibit little or no streaming, the heating process must be continued 
and a trial made on the succeeding day. If the oil becomes too thick it 
will form frothy drops, and in such cases a small quantity of ordinary 
olive oil must be mixed with it. 
The vesiculate drops are prepared thus : — In a small agate mortar a 
small quantity of dry carbonate of potash is ground to a fine powder. 
This must be breathed on till the salt becomes slightly moist, and then 
a drop of oil must be added ; the two constituents should be mixed till 
they form a thickish paste. A few drops of it, about the size of a pin’s 
head or smaller, are placed on a cover-glass, the corners of which are 
supported by small pegs of soft paraffin. Prof. Biitschli then places on a 
slide a drop of water, and puts the cover-glass over it in such a manner 
that the drops of paste are immersed in the water, but are not much 
compressed. The preparation is then placed in a damp chamber, and 
remains there about twenty-four hours, when the drops have a milk- 
white and opaque appearance. The preparation is then well washed out 
with water, which is supplied at one edge by a capillary tube and drawn 
out by blotting-paper at another. 
If the drops have turned out well they will begin almost at once to 
move about rapidly and change their shape continuously. The water 
under the cover-glass must now be displaced by glycerin diluted with an 
equal bulk of water, when a vigorous streaming movement will be exhi- 
bited. The amoeboid movements are generally more distinct if the drops 
are somewhat compressed. If the drops do not stream they can generally 
be made to do so by tapping the cover-glass slightly, by applying gentle 
pressure, or sometimes by breaking up the drops. It is especially inter- 
esting to see how fast and beautifully the drops creep to and fro in the, 
water or in half-diluted glycerin, even when they are not compressed. 
The streaming movement, on the other hand, is better seen if the drops 
are somewhat compressed; this may be done by inserting under the 
cover- glass a piece of broken cover-glass of medium thickness, and then 
removing the paraffin pegs. This streaming movement is best demon- 
strated twenty-four hours after the addition of the glycerin, as the drops 
will then be thoroughly cleared and transparent. The movement and 
streaming are much more marked and distinct if the drops are examined 
on a stage warmed to 50° C. 
* Quart. Journ., Micr. Sci., xxxi. (1890) pp. 99-103. 
t See this Journal, 1889, p. 731. 
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