476 



KNnwij-.nci: 



Decemhkr. 1912. 



The gathuriiiK w;is an unusually large one, and many i.l tin- 

 exhibits were of exceptional interest. 



In the Lecture Tiieatre a cinemato(»raph display of Pond- 

 life was Kiven by Mr. K.J. Spitta, L.R.C.P., F.K.M.S., and 

 this was followed by a lecture entitled " Insects as Carriers of 

 Disease," by Professor K. T. Hewlett, M.D., F.K.M.S.. ilhis 

 trated with lantern slides. 



Mr. Max Poser, F.R.M.S., gave a demonstration of " Licjuid 

 Crystals." which were shown on the screen, both in the solid 

 and liquid phases, by means of a projection apparatus. 



Anion;; the many exhibits in the Large Hall were an L'ltra- 

 niicroscopc Photo-micrographic apparatus, shown by Mr. J. E. 

 Barnard, F.K.M.S.. and an .-\bbe Diffraction Microscope; 

 Ouartz Mercury Vapour Lamp, by Messrs. J. E. Barnard, 

 F.K.M.S., and Powell Swift. Photomicrographs and slides, 

 showing the interesting " Mitotic Phenomena," were shown 

 by Messrs. E. J. Sheppard and H. F. Angus. 



The " Edinger Drawing and Projection Apparatus " was 

 contributed by Mr. J. W. Ogilvy, F.K.M.S., with photographic 

 apparatus, and photo-micrographs by the " Three Colour 

 Process." There were also shown some examples of 

 " Brownian Movement" by Dr. G. P. Bate, F.R.M.S. ; a 

 complete Optical Bench, by Messrs. R. & J. Beck; Diffraction 

 Experiments, by Mr. J. W. Gordon; Slides and Photographs 

 of Foraminifera. by Messrs. E. Heron-.Allen and .Arthur 

 Earland. F.R.M.S.; Mycetozoa, by Mr. C. H. Huish. 

 F.R.M.S. : Trypanosomas, by Professor Minchin, F.R.S. ; 

 Stereo-photomicrographs in colour of water-mitcs. by Mr. H. 

 Tavcrner, I'.R.M.S. ; Chemical Reactions, by Professor 

 Herbert Jackson; Micro-spectra Camera, by Mr. Julius 

 Rheinberg, F.R.M.S.; Interference Figures in Crystals, by 

 Mr. Powell Swift ; Foraminifera, by Mr. Ernest Heath, 

 F.R..\I.S. ; .An old Microscope, by Professor Dendy, F.R.S. ; 

 Photo-micrographic .Apparatus and various Slides, by Mr. 

 Chas. Lees Curties, F.R.M.S. ; Metallurgical Sections by Mr. 

 Max Poser. F.R.M.S.; and Saccharomycotes by Messrs. , A. 

 Chaston Chapman, F^.R.M.S. and R. L. Collett. 



Another feature arranged by Mr. D. J. Scourfield, F.R.M.S., 

 was a exhibition of Pond-life, due to the combined efforts of 

 Fellows of the Society and to various members of the Ouekett 

 Microscopical Club. 



THE QUEKETT MICROSCOPICAL CLUB. — On 

 October 22nd, 1912, Messrs. Heron-Allen, F.L.S.. F.R.M.S., 

 and .A. Earland, F.R.M.S.. lectured on "The Foraminifera as 

 World Builders." Reference was made to the " discovery," 

 half-acentury ago, of Eozoon canadensc in the Laurentian 

 rocks of Canada. .Although by general consent Eozoon is 

 now relegated to the mineral kingdom, Mr. R. Kirkpatrick 

 has recently announced in Xatiirc that he is in possession 

 of fresh evidence of the foraminifera! nature of Eozoon, 

 and will shortly publish it. From the point of view of the 

 lecture definite proof of the rhizopodal character of Eozoon 

 would be welcome, as it occurs in enormous reefs in Canada 

 and elsewhere. There are at present no definite records of 

 Foraminifera in Pre-Cambrian rocks, but in Cambrian strata 

 we liiid the group flourishing and already marked by widely 

 separated types. In Silurian times Foraminifera were not 

 numerous, and in the Devonian there is but a single record 

 (by Terquem.at Patl'rath in the Eiffell. In the Carboniferous, 

 however, Foraminifera begin to be " World Builders," the 

 large arenaceous form, Saccanimina fiisiiUniformis McCay 

 ( = S. Carteri Bradyl, being the principal constituent of enorm- 

 ous areas of limestone in Great Britain and on the Continent. 

 In Permian, Permo-Carboniferous, Triassic, Jurassic, and 

 even Cretaceous rocks, while the number of genera and 

 species multiply enormously, they do not form any important 

 proportion of the whole bulk of the formations. With the 

 Tertiary period we reach the Golden .Age of the I'oraminifera, 

 the age in which they were to reach their maximum develop- 

 ment both as regards size and abundance, and to leave their 

 remains in great beds extending across whole continents, and 

 often of enormous thickness. With the passing of the Eocene 

 the Foraminifera lose their all-important position as rock- 



builders. The genus Xitininiililes. which with Alvcolina 

 built up enormous areas of limestone extending across 

 .Southern Europe to the Himalayas, dies out and dies so 

 coTupletely that at the present day it is represented by only a 

 single small species of rare occurrence in tropical seas. The 

 Miocene and later Tertiary deposits, though often presenting 

 an abundant and extremely varied Foraminiferal fauna, no 

 longer owe their existence to the occurrence of one or few 

 species in enormous numbers. 



To-day, the activity of the Foraminifera is displayed in 

 another sphere. In the surface-waters of the great oceans 

 the few genera which are found swarm in countless numbers, 

 and, their dead shells falling constantly to the sea-floor, are 

 there building up layers of Glohigcrina ooze over an area, 

 according to Murray and Renard, of more than forty-nine and 

 a half million .square miles, exceeding that covered even by 

 the Nummulitic limestone. Of the thickness of the ooze we 

 can form no idea, but as the great oceans are practically 

 permanent it must be very great, because we know from deep- 

 sea deposits which have been elevated into land-surfaces in 

 Malta. Australasia, and elsewhere, that similar deposits have 

 been forming in the deep-sea since at least Miocene times. 



PHOTOGRAPHY. 



By Edgar Senior. 



HXPOSCRE TABLE FOR DECEMBER.— The calcula- 

 tions are made with the actinograph for plates of speed 200 H . 

 and D., the subject a near one, and the lens aperture IM'i. 



Remarks. — If the subject be a general open landscape, take half 

 the exposures given here. 



PHOTOGRAPHING COLOURED OBJECTS.— It is 

 now generally known even among beginners that in a photo- 

 graph of a coloured object, taken upon an ordinary plate, the 

 relative value of the colours " as regards their luminositv " are 

 very badly rendered. Blues photograph too light, while yellow 

 and red are reproduced much too dark. The explanation, as 

 is now well-known, lies in the fact that the silver salts 

 employed are far more sensitive to blue and violet than to any 

 other colour, with the result that blue becomes fully exposed 

 almost before any action has taken place from the yellow and 

 red. From the earliest time this was a great soiu'ce of trouble 

 to the photographer, and Crookes in 1858 suggested the use 

 of a yellow screen, placed in front of the plate, as a means of 

 improving the colour luminosities; but with plates of the low 

 sensitiveness in use at that time such a device was of very 

 little value. With the introduction of the gelatine plate, with 

 its greatly increased speed and general sensitiveness, it was 

 found possible, by employing an extra-rapid plate and a 

 suitable screen, to obtain negatives of coloured objects, in which 

 the luminosities of the colours represented were practically 

 correct. The improvements, however, were at the expense of 

 greatly prolonged exposure. The discovery of the sensitizing 

 action of certain dyes when added to gelatine emulsions at once 

 removed this difficulty, and placed a really practical method 

 at the disposal of photographers. Quite early in the history 

 of photography it had been found possible greatly to modify 

 the .sensitiveness of silver salts by the .addition of various 

 substances to them ; about 1873. Dr. H. W. \'ogel found that 

 the addition of aurine to collodion emulsion resulted in an 



