ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



423 



at a greater anirle than l-o N.A., so that dry object-glasses, or a 

 1-0 X. A. y^^- oil-immersion lens, can be used without stopping-down. 



Fig. 60. 



Higher angle-immersion lenses should have a stop dropped in behind to 

 reduce the aperture to 1 • N.A. 



(6 J Miscellaneous. 



Quekett Microscopical Club. — The 490th Ordinary Meeting was 

 held on May 28, the President, Professor A. Dendy, F.K.S., in the Chair. 

 Mr. T. A. O'Donohoe on " Minute Structure of Coscinodiscus asterom- 

 phalus and of Pleurosigma nngulatum and P. laltkumy The author's 

 object was to determine, if possible, which was the correct image, the 

 " white dot " or the " black dot." 



June 24. H. Sidebottom, " The Lagenae of the South-west Pacific." 

 This was the second part of a valuable paper which appeared in the Club 

 Journal for April 1912.* 



E. M. Nelson, F.R.M.S., "On a New Method of Measuring the 

 Magnifying Power of a Microscope." 



B. Technique. t 

 (1) Collecting" Objects, including- Culture Processes. 



Paraffin as Source of Energy.}: — N. L. Sohngen, by means of ap- 

 propriate cultural methods, has shown that benzin, petroleum, paraffin 

 oil, and various paraffins, may be used by certain bacteria as a food-stuff 

 supplying carbon, and therefore as a source of vital energy. By inocu- 

 lation of material from divers sources upon a culture medium consist- 

 ing of paraffin and inorganic salts, the author shows that a number of 

 bacteria, including Bacillus fluorescens liquefaciens, B. pyocyaneus, etc., 



* See this Journal, 1912, p. 527. 



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

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

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

 (6) Miscellaneous. 



X Centralbl. Bakt., 2te Abt., xxxvii. (1913) pp. 595-609. 



2 F 2 



