26 REPORTS. 
probably the membrane in which they are situated fulfils this office. December 
3rd.—A party of the members visited the brass-founding establishment of Messrs. 
W. Tonks and Sons. Amongst the processes inspected were those of modelling 
the patterns, moulding, casting, tube-making, brazing, polishing, stamping, 
making brass-headed nails, pickling, lacquering, and tool-making. December 11th. 
—Mr. J. W. Pickering read a paper on “‘ The Autotype Process of Photography,” 
which he described as the reproduction of an artist’s work in monochrome by the 
natural forces of light or actinism and chemical affinity, the materials employed 
being those of the artist’s own palette. Mr. Pickering gave a short history of 
photography, from its introduction in 1839 by Mr. Mungo Ponton, who announced 
it as “‘a process of producing images by the action of light on paper which had 
been impregnated with a solution of bichromate of potash,” to its perfection in 
1864 by Mr. Wilson Swan, of Newcastle, who, by temporarily transferring the 
film to another surface, and washing it from its under-surface, succeeded in 
bringing out the half-tones, and thus rendered the process so complete that auto- 
type pictures are incapable of being affected by the atmosphere. The lecture 
was illustrated by a practical demonstration of the process, and an exhibition of 
a fine series of autotype copies of works of art, lent for the occasion by the 
Autotype Company. 
BIRMINGHAM NATURAL HISTORY AND MICROSCOPICAL 
SOCIETY.—Microscopican GENERAL Merntine.—November 19th—Mr. J. 
Levick exhibited Epistylis grandis, Zoothamnium arbuscula, and Carchesium 
polypinwm, all fed upon carmine. Mr. H. H. Forrest exhibited and described a 
simple and easy method of drawing objects under the microscope, of which 
a brief description will be found under the head “ Microscopy,” at page 18. 
GENERAL Mrretinc.—December 3rd.—Mr. W. Southall exhibited a spike of 
fruit of Gunnera scabra, native of Chili. Myr. W. G. Blatch read a paper on 
“Midland Entomology,” which will be printed in the ‘‘ Midland Naturalist.” 
Bronocicat Section.—December 10th.—Mr. H. E. Forrest read a paper on “ the 
History and Development of Zoothamnium arbuscula and some other Vorti- 
cellidz,” which will appear ina future number. Among the specimens exhibited 
were the rare beetle Prionus coriarius, occasicnally found in the south of 
England, and of which Mr. W. G. Blatch now contributed the male taken at 
Aston, in July last ; and marine organisms, shown in the microscope, by Mr. T. 
Bolton, and identified by Professor E. Ray Lankester as the Trochosphere phase 
or larvee of the Polyzoon, Alcyonidiwm hirsutum. In reference to these, Pro- 
fessor Lankester writes, ‘‘These larvee are very interesting objects for study. 
They have the form of a compressed circular disc, or rather of two discs placed 
one on the other. Thelarger one is bounded by acirclet of powerful cilia, the 
‘architroch’ or ‘primitive ciliated band,’ which appears under one form or 
another in so many invertebrate larve. Onthe upper surface of this ciliated 
disc is carried the mouth, which leads into a very remarkable protrusible 
pharynx. The rudimentary digestive cavity is clearly seen in specimens slightly 
compressed by the cover-glass. The ciliated band is what gives rise later to the 
tentacles of the Polyzoon. These larve have never been well figured in England. 
Last year M. Jules Barrois published a large work on the subject at Lille, with 
many plates.” 
BURTON NATURAL HISTORY AND ARCH OLOGICAL SOCIETY.— 
December 10th.—Mr. Ford read an interesting paper on ‘‘ The Gypsum Beds of 
the Triassic Marls of the Neighbourhood.’ He pointed out that gypsum is 
usually considered to be a chemically-formed rock, deposited in the waters of a 
lake or inland sea by evaporation, in the same manner as rock salt. But no 
instances can be pointed out where beds of gypsum are forming at the present 
day in thismanner; and it seems more likely that they are the result of the mutual 
decomposition of carbonate of lime and some sulphide or sulphate. The 
resulting sulphate of lime (gypsum) being soluble in water would be carried in 
solution through the rocks until it arrived at the water level, where it crystallised 
out, filling fissures, &ec. Gypsum can be traced from Chellaston, by Aston, to 
Thrumpton, Gotham, Beacon Hill, Newark, and Bingham. It is also worked 
near Carlisle, and in the other direction at Fauld and Chartley. A thin vein, 
about 14 inches across, occurs in the bed of the Ouse beyond Goole. The 
