SCIENTIFIC SUMMARY. 
397 
on the upper one of which certain granulations are found, which form the 
colouring matter of the scale, and render it more or less opaque. On the 
second membrane, striae frequently exist, consisting of rows of small parallel 
cylinders, like harp-strings, or lines of pearl-like granulations. Of these striae 
there are often one hundred on each scale. The writer believes that there is 
a third membrane in all scales, although it often happens that only two are 
apparent, owing to the transparency of one of them. In diurnal Lepidoptera 
this third lamella has the property of reflecting rich and varied colours, more 
beautiful than those produced by the granulations on the upper membrane. 
The genus Vanessa, and more particularly the exotic species, are particularly 
enriched from this source ; nor are the nocturnal Lepidoptera wanting in this 
respect, the genera Noctuaand Sphynx being examples of brilliantly-coloured 
insects, though they are far inferior to the diurnal species. The rich 
metallic blues and greens of some exotic species, such as Ulysses and Paris, 
arise from a peculiar arrangement of the strife, the intervals between which 
are pretty regularly divided transversely into longish squares, each square 
having within it a funnel-shaped depression. Some scales have the property 
of dispersing transmitted light in a very beautiful maimer under the micro- 
scope ; and a good example, easily met with, of such scales may be found in 
the Gamma Moth (Plusia gamma), in which these scales may be found form- 
ing the pearly or golden bands which are seen below their first wings on the 
inner margin, starting from the base. The presence of granulations on the 
upper membrane adds much to the richness of this optical effect. The 
result of these observations of M. Descliamps seems to be, that “ the”most 
brilliant reflections produced by the scales of Lepidoptera are due rather to the 
arrangement of their lamellce than to the regularity and transparency of their 
strice .” 
Professor Unger, of Vienna, has made a curious observation upon some 
powder from a brick found at Eileithyia, in the Thebaic!, Upper Egypt. On 
examining it under the microscope, he found no less than eight species of 
plants, of which it w r as possible still to make out the species, and similar in 
every respect to species now growing in Egypt and Nubia. The age of this 
brick being between 3,000 and 4,000 years, it would not appear that that 
interval has had any marked effect in changing the vegetation of that country. 
Mr. Thos. Davies, in the Microscopical Journal, has called attention to the 
unworked field presented by the employment of polarized light — unworked 
that is to say, in a proper scientific manner ; for to many so-called micro- 
scopists the exhibition of its pretty effects constitute the whole science, so far 
as they are concerned. 
The most notable contribution to microscopical construction of late has 
been the universal achromatic microscope of Messrs. Smith and Beck. This 
microscope, described and figured in the Microscopical Journal, has for it 
first recommendation cheapness — the sum of five guineas bringing it within 
the reach of many who are separated by an unfathomable abyss from the 
splendid instruments which would cost almost a year’s income to them. An 
instrument made by the most experienced manufacturers at so low a price is 
in itself an advantage ; but the chief merit in their invention is, that it is 
susceptible of numerous improvements and additions, which its possessor can, 
from time to time, make, as his limited funds permit. Thus a body may be 
