SCIENTIFIC SUMMARY. 
215 
Resolution of Amphipleura pellucida. — Mr. R. B. Tolies, an American 
microscopist of considerable note, states, as a fact of interest to microscopists, 
that the resolution of Amphipleura pellucida is not any longer a difficult 
achievement. With a true y^-in. of only 90°, even less than 75°, he has 
repeatedly and plainly lined the valve, using sunlight and blue cell , the speci- 
men of A. pellucida being one supplied to him as a proper test specimen by 
Dr. J. J. Woodward, and received by him from London. This performance 
was not dependent on any special merit in the objective — any good immer- 
sion ^th would do the same thing. To accomplish this he used a narrow 
angled 1-in., 10° swinging under the stage of the microscope as a condenser. 
This 1-in. was placed at the incidence (obliquity to the axis of Mic.) 45° or 
less. The focus for parallel (sun’s) rays a little outside of the object.— 
Monthly Microscopical Journal , March. 
Dr. Reale’s Mode of Demonstrating the Microscopic Structure of Tissues . — 
The mode is that which he has followed for more than ten years, and which 
in his hands has been most successful. He feels sure that it is capable of 
further improvement in practical details, and that, upon the principles which 
he has laid down, delicate structures, which have not yet been seen by 
man, will be demonstrated by patient and well-practised observers. The 
process is troublesome, and for this reason it has not been in much favour. 
In these days investigation must be conducted with such haste, and 
new facts discovered so quickly, that there is little chance of getting many 
persons to spend sufficient time in mere practice to enable them to gain the 
requisite skill for the very much more minute investigation of the structure of 
the most delicate textures which is now so much required, and which must 
be carried out before we can hope to arrive at positive conclusions on funda- 
mental anatomical questions of the greatest importance. — M. M. J., March. 
Oblique Illumination. — Dr. J. Miller gives, in the “ Microscopical Journal” 
for January, an account of Col. Horsley’s cylinder for this purpose. This 
instrument is 1| inch long, and l£ inch in diameter, made of brass tube 
silvered inside. The light is thrown on to it either directly, or from prism 
or bull’s-eye used as a prism. A dark ground is easily got with low angle 
f-inch, and without trouble or loss of time the hemispheres of Angulatum 
are shown very beautifully. The first apparatus was made by silvering the 
inside of the tube of the sub-stage which carried the polarizer ; this was 
done by rubbing on it a solution of nitrate of silver, to which hyposulphite 
of soda had been added. This silvers brass with a good surface, and mode- 
rately permanent, in a moment. 
Prizes for London Microscopists . — A series of prizes has been offered by 
the Countess of Ducie to those who work at the ponds and streams of the 
London neighbourhood. The prizes are three in number : one 51., one 3/., 
and one 2 1. They are to be awarded on March 31, 1873. The conditions 
may be had by writing to Secretary Natural History Prizes, 100 Fleet Street, 
E.C. The adjudicators are Henry J. Slack, Esq., F.G.S., Secretary of the 
Royal Microscopical Society, author of “ Marvels of Pond Life,” &c., &c., and 
Walter W. Reeves, Esq., F.R.M.S., Assistant-Secretary to the Royal Mi- 
croscopical Society. 
1 A New American Microscopical Journal . — Just as we go to “ press,” the 
first number of the new Chicago journal reaches us. It is called “The 
