NOTES AND QUERIES. 215 
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Mr. Moller also issues type plates of 100 and 4oo diatoms with 
the names of each photographed beneath. 
All the type plates are mounted in monobromide of naphthaline. 
Twenty-four test objects (diatoms) are now issued in eight 
different forms—viz., in air, balsam, monobromide of naphthaline, 
and phosphorus, and with cover-glasses of 0.16, 0.20 mm., or 
0.06, 0.08,mm. These include Amphipleura pellucida, Frustulia 
Saxonica, Pleurosigma angulatum, and Surirella gemma. The 
“ Probe-platten ” of 20 and 60 diatoms are also supplied in the 
four different forms of mounting. —See /,R.JZ.S., June, 1883. 
DECOMPOSITION OF SYNEDRA RADIANS BY CausTIC PoTAsH.— 
C. J. Miiller calls attention to the action of a solution of caustic 
potash on the frustules of Sywedra radians, fresh gathered, or, at 
least, in a living state. The solution used is composed of 50 
grains of caustic potash dissolved in 1 ounce of distilled water. 
Having placed the diatoms (more or less intermixed with other 
forms) in a moist state upon a glass slide, and allowed the mass to 
get nearly dry, apply the solution of potash freely and cover with 
thin glass. After the lapse of a few hours (more or less according 
to temperature) it will be seen—in the case of a front view of a 
frustule—that the connective will separate as two fine siliceous films 
in a curved form, one belonging to one half of the frustule, the 
other to the other half. 
In the case of a side view of a frustule in the process of division, 
the two portions will separate at the extremities, expanding there- 
from in a curvilinear form. 
After a further time it will be seen that the portion of the siliceous 
shell which contains the striation will be entirely separated from 
the endochrome, and in many cases greatly curved. 
After the lapse of 24 or 36 hours, it will generally be noticed 
that the siliceous portion containing the striation has broken up 
into fragments which are exactly like the iron cramps of carpenters. 
In fact, the striation is due to the juxtaposition of a number of 
these little cramps along the length of the frustule, probably 
cemented together originally. 
Synedra radians may be described as a long four-sided box, two 
of the sides (top and bottom) consisting of a siliceous film without 
any markings, and the other two sides of a structure made up of 
cramps holding the upper and lower side in position. 
Mr. Miiller adds: “I should have liked to illustrate this dis- 
covery, but any one familiar with microscopical manipulation will 
be able to see all that I have described better on the stage of the 
Microscope than in a drawing on paper. A power of 250 or 300 
diameters is sufficient for the observation. The success of the 
experiment depends a great deal upon temperature, the purity of 
