NOTES AND MEMORANDA. 
317 
BeicJiert and Du Bois-Beymond's Archives, part 1, 1876. — On the 
Anatomy of the Leaf of Dioncea muscipula, by Herr F. Kurtz. 2 plates. 
— Part 2. The Allantois in the Embryo of Man, by Professor W. Krause. 
Nuovo Giornale Botanico Baliano. — (The contents of these are thus 
given by ' Nature,' July 6.) The two last numbers are chiefly occupied 
with Italian botany, viz. on the Structure of the Wood of Periploca 
grceca, by Signer A. Mori, and other papers, hardly of interest to the 
microscopist. 
Archiv fur Naturgeschiclite. Edited by Dr. Troschel. Forty-second 
year. 1st Heft, — An interesting paper, accompanied by two good plates, 
on Helminthological Studies, by Dr. von Linstou.— On the Development 
of the Mites, by Dr. P. Kramer. This has one plate connected with 
it. — On the Natural History of a species of the family Gamasidice; 
also with a plate, and by the last-named author. 
Annals des Sciences Naturelles. 6th series. — Botany : Development 
of Scleroderma verrucosum, by M. N. Sorokine. This is illustrated by 
a pair of excellent plates. — The same author has written the following 
papers : " A New Genus of Myxomycetes," and also " A Few Words on 
the Development of Aphanomyces stellatus'' — The last paper in this 
number which is of interest to the microscopist is on the reproduction 
of Ascomycetes, a microscopical and morphological study, by 
M. Max Cornu. 
NOTES AND MEMOEANDA. 
The Fluorescent Ray for Microscopic Purposes. — At a late 
meeting of the Academy of Natural Sciences of Philadelphia, some 
remarks on which we shall not comment were made by one of the 
academicians. They are thus reported : — Professor Frazer spoke of 
thinness or minuteness of objects under the microscope, and suggested 
a method of studying, by means of the fluorescent ray, objects at 
present invisible to the highest powers. Dr. Hunt stated in reply 
that microscopists were not willing to be limited in their observa- 
tions by the calculations of mathematicians, and that the comparative 
darkness of the fluorescent ray would not be favourable to investi- 
gations of the kind. 
Effect of Aperture on Definition. — Mr. J. Zentmayer, in a very 
clear lecture on the elementary properties of lenses, published in the 
' Journal of the Franklin Institute,' May and June, 1876, and which 
we should reprint were it not for the number of illustrations it would 
require, calls attention prominently to the confusion of images neces- 
sarily attendant upon large apertures, except when viewing absolutely 
flat objects, from the stereoscopic character of the images formed 
by different portions of the surface of the lens, the image formed by 
pencils transmitted by one side of the lens being unavoidably different 
from corresponding images formed by the opposite side of the lens. 
