44 THE MICROSCOPE. 



diarrhoea, etc., and the lungs, liver, and spleen were found to be 

 tuberculated. In the protected box, on the contrary, the rabbits 

 were still perfectly healthy, and on autopsy not a trace of tubercu- 

 losis was to be found. — Comptes Rendus. 



Prussian Blue and Safrane for Plant Sections. — Prof. J. 

 Brun refers to the process of double staining for vegetable histology 

 described by him to the Geneva Physical and Natural History 

 Society, in which the action of Prussian blue alternates with that of 

 safranine. The process is to be recommended for the clearness with 

 which the preparations show all the minutest details, even in the 

 interior of the cells. The chlorophyll retains its color, while the 

 cellulose, the layers of the cell-walls and their contents, the incrust-' 

 ing matter, and the fatty or resinous substances are, on the con- 

 trary, differently colored and readily differentiated. He insists on 

 the value of these histo-chemical processes in distinguishing very 

 minute transparent bodies, and above all to differentiate organs 

 scattered through opaline liquids or colorless histological elements. 

 — Journal de Mic. 



Objectives of Large Aperture. — Dr. J. Pelletan criticizes 

 Dr. Carpenter's remarks on this subject at Montreal, and in regard 

 to injury to the eyesight suggested as the result of the use of a T 4 lT 

 in. of large aperture, considers it an ''accusation as well founded as 

 to say that too large a hat will produce corns on the feet." If it is 

 the fact that certain objectives may injure the sight it is the high 

 powers with small angle, deficient in light, resolving badly, and 

 requiring " efforts of vision," so to say, rather than the relatively 

 low powers of large angle, bright, and showing at once the image 

 of the object clearly resolved. He also claims as conclusive evidence 

 in favor of the necessity of objectives of the largest aperture the 

 admission of Dr. Carpenter that the flagella of Bacterium termo 

 could not have been discovered without such objectives. The Yz 

 in. of 40" could not be of any use to a microscopist for delicate 

 and serious observations, neither to the diatorriist nor to the investi- 

 gator of the histological elements who requires a large aperture to 

 enable him to follow a fibril layer by layer so as to determine all the 

 relations of its position and the precise point where it ends. — Royal 

 Mic. Journal. 



Reticulated Structure of Living Matter. — At a recent 



