51 





THE PRESIDENT'S ADDRESS. \# 



A REVIEW OF PHOTO-MICROGRAPHY. 



By E. J. Spitta, F.R.A.S., F.R.M.S. 



(Delivered February loth, 1907.) 



Owing to the improvements effected in later years in the 

 construction of objectives — more especially, perhaps, those of 

 very high powers — through the introduction of the Jena glass, 

 the reproduction of objects or portions of objects by photo- 

 graphy used in conjunction with the microscope has become 

 not only a possibility, but a matter of everyday use for scientific, 

 as well as commercial, purposes. Looking back, it is difficult to 

 be quite certain who really made the first photo-micrograph. In 

 January, 1906, M. A. Nachet, F.R.M.S., presented to the Royal 

 Microscopical Society a frame containing six photo-micrographs 

 taken with the electric light by Leon Foucault with the Daguer- 

 reotype process in 1844. The subjects were two of mammalian 

 and one of reptilian blood corpuscles, one of milk, and two of 

 crystals. Each of the silver plates was signed by M. Foucault, 

 and the month and year were also added. The magnification 

 attained in the case of the blood corpuscles was about 500 

 diameters. This is believed to be the earliest application of 

 the electric light in photo-micrography, although, of course, 

 many photographs with the microscope had been obtained prior 

 to this. For instance, in a work on the Microscope by 

 Lardner, published in 1856, it is stated that in 1845, Dr. Donne, 

 of Paris, published through Messrs. Bailliere, of London, an 

 atlas of a course of lectures on " Anatomy and Physiology," 

 which he had given during the previous year, containing 

 twenty plates, each with four reproductions of daguerreotypes 

 made with the aid of the solar microscope. A reproduction 



