1892.] THE MICKOSCOPE. 175 



ognitoin of several series of preparations showing thoughtful and 

 able study of interesting subjects mostly connected with insect 

 and plant life. 



A notable feature of the exhibition was the free use of the 3x1 

 in. slides by continental preparers, in preference to the various so- 

 called continental sizes. If confined to professional preparers this 

 might be considered a concession to the requirements of English 

 and American buyers ; but being noticed also in the work of 

 those who prepare for their own use, it goes far toward indicating 

 that, in spite of its well-known minor disadvantages, the 3x1 

 standard was not a very undesirable selection. 



Literature. 



The invitation for an exhibition of microscopical books secured 

 only a few responses. The owners of valuable volumes are loth 

 to be separated from them for months ; and the possessors of 

 priceless rarities of this kind w^ould seldom care to trust them in 

 a public exhibition where to be of any real use they must be 

 handled freely b}- the visitors. Of modern publications, only 

 the two French journals and a limited number of books and 

 pamphlets on the microscope, diatoms, botany, etc., appeared. 



One of the smallest and most unpretending of the works was 

 certainly one of the most remarkable; a little book on '•^ Sept 

 Objects Regardes au MiC7'oscope.'' by Dr. E. Giltay, profes- 

 sor of botan}^ in the National School of Agriculture at Wageningen, 

 Holland. The seven objects are : i, colored lines on opposite 

 sides of an object slide ; 3, a cylinder of smoked glass ; 3, starch ; 

 4, air bubbles ; 5, milk; 6, collenchyma ; 7, an Abbe ditiraction 

 plate. In describing very plainly and briefly the study of these 

 simple objects a great amount of valuable information is intro- 

 duced concerning microscopical manipulation, observation, and 

 interpretation. Small as this book seems, it is actuallv only 

 half as big as it looks, every second page being a duplicate, 

 repeating in French the substance of the opposite page in Dutch. 

 In this ver}' practical way the little book appeals to a greatly 

 enlarged circle of readers. 



Among the larger exhibits were several works by Dr. Wm. 

 Behrens ; and seven volumes by Dr. J. Pelletan. of Paris, in ad- 

 dition to the fifteen volumes of his ^^ Journal de Micrograpie^''' 

 the whole representing an extraordinary amount of able work. 



Dr. Henri Van Heurck exhibited the four editions of his trea- 

 tise on the microscope, the two grand volumes of his •' Synopsis 

 des Diatoniees de Belgique^^'' with its atlas of 3,100 figures, and 

 seventeen pamphlets. These, in connection with his large col- 

 lection of interesting antique microscopes, his apparatus for 

 electric lighting, for photomicrography, for micrometric ruling, 

 etc., his unsurpassed photomicrograms of diatoms and other test 



