SCIEJ^TiriC SUMMAEY. 
103 
Eupodiscus Argus Eroperly Examined. — Mr. Slack says that when Mr. 
'Wenham’s reflex Illuminator is successfully employed upon Eupodiscus 
Argus a considerable portion of the circular valve will become clear and 
plain, and it will be seen that it is entirely composed of spherules of 
different sizes and varied aggregation. Radiating from a central portion, 
occupied by minute and closely-packed spherules, bands will be seen pro- 
ceeding to the circumference each one composed of minute spherules, that 
appear in close contact under an with eye-pieces up to D of Ross’ system. 
Between these bands are larger spherules, frequently, but by no means uni- 
versally, arranged in fours, so that when seen with powers too low for their 
distinct separation, they appear to form patterns like the Gothic quatrefoils, 
and look like holes when the light passes straight through them. — Monthly 
Mici'oscopical Journal (Dec. 1872). 
Tolled Nexo Wet-Ohjective -l^th. — On this Dr. Woodward speaks most favour- 
ably. For instance, with regard to the performance of the dry combinations 
of this objective, he merely says that they gave him the striae of Amphi- 
pleura pellucida rather better than any dry objective he has ever tried. 
He has not tested them as yet to any extent on other objects, because of the 
manifest superiority of the immersion work. The behaviour of the objective, 
when used wet, is certainly admirable. In illustration, he forwarded to the 
Society a new series of views of Nobert’s plate from the lowest to the 
highest bands taken by it. These pictures, which certainly excelled all 
his former work on the plate, were purposely taken from the ordinary 
thick-bottomed plate, accessible to most microscopists, in order that those 
interested might compare what they can see by their objectives with the 
work then submitted. Most of the negatives were made with a power of 
about 1,200 diameters ; but as paper prints of the 19th band, with this 
power, are so indistinct as to be practically valueless, he has added one of 
the 19th band from a negative taken with about 1,800 diameters, one of the 
15th, for comparison, taken at the same distance, with the same cover cor- 
rection ; and lastly, an eulargement of the 19th band picture, which he 
hoped would serve to illustrate the subject of spurious lines on the edges of 
the band, as well as to display the flne resolution of the real lines obtained 
by the objective employed. It will, of course,” he says, ‘^be expected 
that I should say something of the comparative merits of this new objective 
of Mr. Tolies, and the immersion front of the Powell and Lealand i\th, 
which has done so much good work for me since 1869. Certainly, I must 
give the new Tolies’ objective the preference on the plate, and on Amphi- 
pleura pellucida, both by sun and lamplight. On other tests, I have not as 
yet done enough work to particularize.” — Monthly Microscopical Journal 
(Nov.) 
The “ Miniature Method ” of Estimating Objectives. — This mode has been 
well described by Dr. Pigott at the last meeting of the Royal Microscopical 
Society. The method which he calls the miniature method is as follows : — 
Place the object-glass in the position of a condenser. At exactly ten inches 
from the stage, adjust a scale of inches and tenths. Bring the image of the 
scale upon ground-glass slide, with its ground surface downwards. The 
ground-glass now shows a miniature of the scale. Now replace it by a 
micrometer slide, and viewing it with a low power, readjust the condensing 
