NOTES AND QUERIES, 145 
HoMocENEovus IMMERsION.—At the April meeting of the Royal 
Microscopical Society, Mr. Powell exhibited a new 4th homogene- 
ous immersion objective of numerical aperture 1.47 or 150° balsam 
angle. While on this subject we should like to call our readers’ 
attention to the April number of the Journal of the Society, which 
is most interesting to all microscopists who wish to understand the 
subject of “angular aperture.” 
ATMOSPHERIC Dust.—On the morning of the 27th of March 
last, a deposit of reddish-yellow dust fell at Catania in Sicily. 
Very strong south-west winds had blown for several days previously. 
The dust continued to deposit during twenty-four hours, the sky 
was covered with clouds, and a thunderstorm was anticipated ; all 
day a fog hung in the air which was painful to the eyes, and next 
day the leaves of trees were found covered with a fine powder like 
brick dust. 
A SLIDING STAGE-DIAPHRAGM.—At the seventh meeting of the 
present session of the Royal Microscopical Society, a paper was 
presented by Dr. Anthony on the above subject. Mr. Beck very 
properly described the plan ‘‘as old as the hills.” We have used a 
diaphragm made from a sheet of blackened aluminium for the past 
eight years, and upon this the object slide is placed. Mr. Crisp 
added that of late years the importance of using the diaphragms 
immediately beneath the object had become more and more re- 
cognised. 
An InsEcTror1uM.—A remarkable and novel feature has been 
added to the London Zoological Gardens in Regent’s Park, in the 
shape of an insect-house, wherein the entomologist, Mr. Watkins, 
is forming a carefully-chosen collection of creeping and flying 
things. The insectorium is already rich in beetles with burnished 
wings, in butterflies which glitter in gold and purple, in curious 
water insects, and industrious spinners of silken threads. The 
chrysalids are shown in life on the boughs in a box below, and till 
the perfect insects emerge from the plain cocoons in their beauty 
of painted wings, dried specimens of the same are placed above. 
DEVELOPMENT OF FLOWERS.—At a recent meeting of the Pen- 
dleton Field Naturalists Society, Mr. Thos. Whitelegge, of Ashton, 
read a paper on the Development of Flowers. Plants, he said, 
have two modes of reproduction, viz., sexual and asexual. In the 
higher cryptograms the antheridia and archegonia are either on 
one or two organs. Mosses continue to produce flowers for several 
generations, but ferns only do so once. The prothallus soon dies. 
In the Jersey fern, however, the prothallus is persistent, living after 
the fern dies. The capsule of the moss is the only part that has 
stomata. Selaginella produce two kind of spores, the macro and 
micro spores, the larger producing archegonia, and the smaller or 
