ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 231 



quality balsam was found in any of the experiments, but a number of 

 the photographed specimens showed definite right-angled fractures 

 occasionally observed in torn gelatin films. 



British Resources of Sands and Rocks used in Glass Manufacture, 

 with Notes on certain Refractory Materials.* — The above is the title 

 of a valuable Supplementary Memoir, by P. G. H. Boswell, with contri- 

 butions by W. B. Wright, H. F. Harwood, and A. A. Eldridge. The 

 title gives a clear guide to the contents, seven chapters of which deal 

 exhaustively with the raw materials suitable for glass manufacture found 

 in the British islands ; there is also one chapter devoted to American 

 grade glass-sands. The book includes elaborate tables of mechanical 

 and chemical analyses, and some of the plates are microphotographs of 

 British and American grlass-sands. 



o^ 



Petrographic Microscope. f — F. E. Wright's contribution on this 

 subject is an interesting exposition of the possibilities of petrographic 

 •examination. He does not deal much with constructional principles, 

 but limits himself to a description of the results which can be obtained 

 with the view of advocating a wider use of the instrument. 



B. Technique.! 

 CI) Collecting: Objects, including' Culture Processes. 



Medium for Cultivating Bacillus tetani.§ — W. J. Tulloch has 

 discovered the following selective medium for the enrichment of B. tefcfii 

 against other organisms accompanying it. The prepai'ation of the 

 medium is as follows : — Take 1 lb. of chopped meat, add 1 litre of 

 Avater, boil 30 minutes, cool to 45° C, adjust reaction of fluid so that it 

 is slightly alkaline to litmus. Trypsinize as for Douglas's broth ; 

 incubate in open vessel for five days at 37° C. Filter products of 

 putrefaction through paper, add sodium formate 1 p.c. of total, adjust 

 reaction of fluid to neutral point for phenolphthalein. Fluid is then 

 filtered through a Berkefeld and Doulton filter in series, stored under 

 paraffin in sterile flask mounted with a hooded delivery pipette, so that 

 medium may be distributed into tubes. Before use each tube of 10 c.cm. 

 is <5nriched by addition of \ part of fresh rabbit kidney, removed (after 

 Jiiiling animal) by sterile operation. Author usually employs tubes 

 containing 5 c.cm. of medium and adds -^^ part of kidney to each. To 

 ensure sterility, 5, 1, 0"5, O'l, and O'Ol c.cm. are inoculated into meat 

 tubes which are incubated anaerobically for fourteen days and should 

 show no evidence of growth. 



* Longman, Green and Co., London, 1917,92 pp. (7 pis. and maps). 



t Trans. Optical Soc. Amer., i. No. 1, Jan. 1917, pp. 15-21 (1 pi.). 



X This subdivision contains (1) Collecting Objects, including Culture Pro- 

 cesses ; (2) Preparing Objects ; (3) Cutting, including Embedding and Microtomes; 

 (4) Staining and Injecting ; (5) Moimting, including slides, preservative fluids, etc.; 

 (6) Miscellaneous. 



§ Lancet, April 20, 1918, p. 578. 



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