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BIRMINGHAM NATURAL HISTORY SOCIETY. 
observation. From that time photography has been pressed into 
the service, and no fewer than 44 have been found within the last 
lifteen months. Professor Charlois, of Nice, reports the finding of 
six during the last week, a feat which would have been considered 
unparalleled at the beginning of the century.” This, I think, con¬ 
clusively proves the superiority of photography in special work of 
this kind. The above is only one of the many applications of 
photography for recording astronomical phenomena, all of which 
have been of great service. 
It is equally applicable to microscopical investigations ; and a 
much more correct idea of the structure or the nature of the 
markings in various minute organisms, has been gained by its use, 
than could have been arrived at by eye observation alone, notably, 
the splendid photo-micrographs of some of the Diatomaceae, which 
have been taken with the most perfect and powerful objectives made. 
It is impossible to predict to what extent the aid of photography 
will be found useful in deciding obscure physiological questions. 
Professor Exmer, of Vienna, has succeeded in taking a photo¬ 
micrograph of the image which is formed at the back of the 
compound eye of an insect. This image he found to be precisely 
the same as that which would be presented at the back of the 
single eye of one of the higher vertebrates.* As the physiology 
of the arthropod eye has been the subject of much discussion and 
diversity of opinion, this discovery may be the means of throwing 
a new light on the question, and, if so, it will be another of 
the triumphs of photography in elucidating this and similar 
phenomena. 
It is impossible to predict what time will bring forth, but we 
may be sure that with the advance in scientific knowledge, and 
increased facilities for original research, Nature will have to give 
up many secrets, which are as yet only foreshadowed in the minds 
of some of the more advanced thinkers of the present day. May 
our Society be privileged to assist, even in the smallest degree, in 
contributing some new knowledge which may be useful in forward¬ 
ing so desirable a result. 
(To be continued. ) 
* “ The Microscope and Its Revelations,” 7tli edition, page 908. 
June, 1893 . 
