PROCEEDINGS OF THE SOCIETY. 
413 
W. West, Esq. : — Tube-building Rotifer, Melicerta ringens. 
G. Western, Esq. : — Rotifera : Melicerta tubicolaria, Ilydatina senta , 
Conochilus volvox, &c. 
T. C. White, Esq. : — Vertical Section* of Eye of Dragon-fly ; Horizontal 
Section of Human Scalp. 
W. D. Wickes, Esq:— Crystal of Sulphate of Copper and Magnesia; 
Platinocyanide of Tetrium. 
Meeting of 18 th April, 1894, at 20 Hanover Square, W. 
The President (A. D. Michael, Esq., F.L.S.) in the Chair. 
The Minutes of the Meeting of 21st March last were read and 
confirmed, and were signed by the President. 
The List of Donations (exclusive of exchanges and reprints) received 
since the last meeting was submitted, and the thanks of the Society were 
given to the donors. 
From 
S. H. Gage, The Microscope and Microscopical Methods. (5th 
edition, 8vo, Ithaca, N.Y., 1894) The Author. 
Two Photomicrographs of young Fat Cells from foetal Cat . . Dr. W. C. Borden 
Prof. F. Jeffrey Bell called attention to the copy of the 5th edition 
of Prof. Gage’s work £ On the Microscope and Microscopic Methods,’ 
which would be found to be a distinct advance upon previous editions. 
It would be seen that the author had in this edition largely availed 
himself of Dr. Dallinger’s work, which had been published since the 
last issue. The present book could be well recommended as likely to 
be useful to students; it was illustrated by 153 figures. 
Dr. W. H. Dallinger said that a stereoscopic photomicrograph had 
been sent for exhibition by Dr. W. C. Borden, the object being a 
specimen of Helicpelta. It might possibly have its advantages, but he 
was not yet quite able to see what these were. It was a photo-slide on 
which were two photomicrographs, but the stereoscopic result was not 
very apparent. The result, however, might be judged by the Fellows 
who would have the stereoscope and the photograph passed round to 
them. 
Dr. Dallinger also said that at the last meeting of the Society he 
read a letter * from Dr. H. G. Piffard in reference to a method which he 
had adopted for the examination of some of the old immersion objectives, 
and that he had found that one of them by Powell and Lealand had an 
angle as a water-immersion of 143°, which was equal to a numerical 
aperture of 1*26, and that this same objective worked well with cedar 
oil and gave N.A. of 1*44. More recently he had found that this 
objective would correct perfectly with monobromide of naphthaline. 
His next investigation showed that this objective of 143° with the 
* See this Journal, p. 286. 
