ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 819 



down the tube, and the nearest end was in both cases placed at such a 

 distance as to give the same sized image of the object. It will be noticed 

 that the telephoto lens gives a totally different and less steep perspective 

 effect than the ordinary lens. 



C6) Miscellaneous. 



Quekett Microscopical Club. — The I76th Ordinary Meeting of the 



Club was held on Tuesday. October 24, the President, Professor E. A. 

 Minchin, M.A., F.Z.S., in 'the Chair. A paper by Mr. E. M. Nelson, 

 F.R.M.S., on "An Improved Compound Microscope by James Mann, 

 1751," was read by the Hon. Sec. It is, in the main, a copy of J. Cuff's 

 (1744), with various improvements. It is less heavily built, however, 

 and is probably the second Portable Compound Microscope. The instru- 

 ment originally belonged to the celebrated Dr. Johnson. "A General 

 Account of the Spring-tails (Collembola) " was given by Mr. J. W. 

 Shoebotham, N.D.A. Together with the orders Protura and Thysanura, 

 they belong to the sub-class Apterygota, class Insecta. The various parts 

 of the Collembola were fully described, especial attention being given to 

 the very typical organs, the ventral tube and the spring. Previously 

 considered to be scavengers only, it is now thought that they may do 

 considerable damage to growing crops. In Ireland they have been found 

 feeding on the leaves of tobacco plants. Nearly 500 species have up 

 to the present been recorded, of which 107 are British. 



B. Technique.* 

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



Cultivation of Spirochsetes.f — G-. Arnheim gives an account of his 

 microscopical and cultural investigations of spirochetes associated with 

 gangrene of the lung and ulcerating carcinoma. He finds in these 

 lesions a definite species of spirochete, of which, however, the colonies 

 cannot be distinguished from those of other species. These spirochetes 

 are found in carcinomata both of men and of animals, and have been 

 found in the blood of normal rats and mice. They cannot be demon- 

 strated in growths that have not ulcerated. 



For his cultivation experiments the author uses a modification of 

 Schereschewsky's method. Material containing spirochetes is introduced 

 into horse-serum, which has been heated for a short time to 75° C. For 

 the isolation of spirochaetes from a mixed culture, it is necessary to 

 examine various portions of the mixed growth for the presence of these 

 organisms, and replant it in successive attenuations. 



Pure Cultures from a Single CelLf — S. L. Schouten has improved 

 his method § for isolating single cells under the Microscope. In the 



* This division 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. 



t Centralbl. Bakt., lte Abt. Orig., lix. (1911) pp. 20-34. 



J Konink. Akad. Wetenschap. te Amsterdam, xiii. (1911) pp. 840-50 (1 pi.). 



§ See this Journal, 1901, p. 331. 



