ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 263 



Minute Structure of Bacteria.*— A. Amato employs the following 

 method for studying the minute structure of bacteria. A thin layer of 

 alcoholic solution of " brillant kresylblau " is spread on an object-slide, 

 the alcohol is allowed to evaporate, and a drop of broth-culture of the 

 organism to be examined is placed on the slide. If a solid culture be 

 used, a loopful should be mixed with a drop of broth. In tins way 

 physical and chemical actions of fixation processes are avoided, and the 

 form of the bacterial cells is almost unchanged. 



The author gives drawings of the appearances observed in the potato 

 bacillus, Bacillus subtilis, B. mycoides, and Spirillum volutans, of 

 nuclear-like bodies and granules which he regards as nuclear equivalents. 



Metallography, etc. 



Colour-photography in Metallography.f — L. Revillon and P. 

 Beauverie have used autochrome plates with much success. The yellow 

 screen supplied by Lumiere was quite unsuitable for use with the 

 Nernst lamp, the light from which was found, indeed, to contain an 

 excess of red rays. When a green screen (a solution of picric acid and 

 methylen-blue) was used, the colours obtained on the plate corresponded 

 with those observed by eye. Four reproductions of colour-photo- 

 micrographs are given, one of a 20 p.c. nickel steel, cemented, the other 

 three of bronzes and brasses, which were etched by immersion in a boil- 

 ing 50 p.c. solution of caustic soda, to which had been added a few drops 

 of oxygenated water. This etching reagent is recommended for general 

 use with alloys of copper. 



Resilience, and Testing by Impact. J — Resilience has been defined 

 as resistance to shock expressed in kilogrammetres per square centi- 

 metre of original cross-section. L. Revillon has investigated the effect 

 upon this " specific impact work " § of variation in dimensions of test- 

 piece and in distance between supports. A Guillery machine was used. 

 The energy absorbed is greater the less the distance between supports. 

 If, however, all the dimensions of test-piece and also the distance 

 between supports are altered in the same proportion, energy absorbed 

 per unit area is then the same. The results of shock tests should 

 always include an exact statement of the conditions of the test. 



Shock-tests at Different Temperatures. || — L. Guillet and L. 

 Revillon have determined the work absorbed in rupture, in the Guillery 

 machine, of eight different steels, at temperatures ranging from 20°- 

 650° C. Resistance to shock increases up to about 200° C, then falls to 

 a minimum at 475° C, again increasing at higher temperatures. There 

 is no relation between resilience and the transformation temperatures. 

 The results do not indicate that steel is brittle at a " blue heat " (300°- 

 325° C). 



Temper-colours.1[— L. Guillet and A. Portevin find that the oxida- 

 tion tints produced on a bright steel surface depend not only on the 



* Centralb. Bakt., It" Abt. Orig., xlvii. (1908) p. 385. 



t Rev. Mefcallurgie, v. (11)08) pp. 885-6 (4 figs.). : Tom cit., pp. 887-92. 



§ See this Journal, 1908, p. 261. 



|| Rev. Metallurgie, vi. (1909) pp. 94-101 (2 figs.). f Tom. cit., pp. 102-4. 



