ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 341 



confusion is the smegma bacillus ; hence if the urine is to be examined 

 for tubercle bacilli, it should be drawn off with aseptic precautions, 

 and the acid-decolorised films further treated with alcohol for at least 

 30 minutes. 



Error in diagnosis is frequently due to the fact that cultures only- 

 are made and no films prepared. For example, the films may sLow an 

 organism which has failed to grow because the composition or the 

 environment of the media has been unsuitable. Whenever possible 

 films should be prepared and stab cultures made in glucose media. 



Action of Formalin on -Foul-brood of Bees. * — Prof. B. Galli- 

 Valerio has found that hives infected with Bacillus alvei may be 

 effectively purified by the action of formalin vapour. The applications 

 are frequent and discontinuous. The formalin is applied by means of 

 a spray apparatus specially constructed for the purpose. 



Experimental Vaccinia, j — Dr. A. Calmette and Dr. C. Guerin have 

 reinvestigated the observations of Gailleton and others relative to the 

 receptivity of the rabbit for vaccinia. They find that the inoculation of 

 vaccine on a rabbit is always followed by a confluent eruption of lymph- 

 vesicles, provided that the skin be merely shaved and not scratched. 

 The rabbit is an excellent control for ascertaining the virulence of 

 vaccine derived from heifers and infants, and also of gl ycerinated vaccine. 

 Only the skin participates in the multiplication of the vaccine elements. 

 Aseptic vaccines may be obtained by inserting the virus in the peritoneal 

 sac of rabbits after previous injection of bouillon. After a few hours 

 the vaccine is purified of bacteria by the agency of leucocytes, which do 

 not affect the vaccine virus. 



Photography by Means of Photo-Bacteria-:}: — K. Dubois has taken 

 photographs by the light emitted from cultures of photobacteria. Ten 

 to twelve hours were required to obtain a good negative, which shows 

 that the number of chemical rays is very small in proportion to the 

 light rays. The same remark applies to the heat rays. 



Relation of the Chemical Composition and Microscopical Structure 

 to the Physical Properties of Iron and Steel.§ — In the course of his 

 report at the third International Congress of Chemists at Vienna, H. 

 Juptner von Jonstorff summarises the structural characters, which may 

 be microscopically distinguished in pure carbon steel, as follows : — 



1. Blow-holes. 



(a) If rough, they are empty, or contain air. 



(b~) If smooth, they contain hydrogen and carbon monoxide. 



2. Slag. 



3. Graphite, in thick flakes, which in section appear as straight or 

 crooked lines ; they are often detached by the polishing, and leave 

 " graphite crevices " easily seen under the Microscope ; only found in 

 iron rich in carbon. 



4. Ferrite, i.e., pure (or nearly pure) iron ; only found in steel poor 

 in carbon. 



* Centralbl. Bakt, l te Abt., xxix. (1901) pp. 127-9 (2 figs.). 



t Ann. Inst. Pasteur, xv. (1901) pp. 161-8. 



% C.R. Soc. de Biol, cle Paris, liii. (1901) pp. 133-4. 



§ Metallographist, i. (1899) pp. 222-47 (4 figs.). 



June 19th, 1901 2 a 



