458 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



partially or entirely closes the aperture G, the motion of the lever H 

 against the scale K recording the brilliance of the illumination. The 

 apparatus is made by R. & J. Beck. 



Fig. 87. 



Quekett Microscopical Club. — The 482nd Ordinary Meeting was 

 held on May 28, l'J12, Dr. E. J. Spitta, Vice-President, in the Chair. 

 Mr. E. M. Nelson wrote that he had examined a mount of Mr. Siddall's 

 diatoms showing the so-called " pseudopodia." Structure was observed 

 inside the filaments in two cases, one a Coscinodiscus and one a Biddulpkia. 

 Mr. R. T. Lewis, F.R.M.S., read " A Note on Solpuga {ferox ?)." About 

 fifty species of this Arachnid are known, all African. The specimens 

 described were from Lindley, O.R.C. Preparations were exhibited under 

 Microscopes. Mr. A. E. Conrady, F.E.A.S., described " Some Experi- 

 ments on Alternative Microscopical Theories." 



The 483rd Ordinary Meeting was held on June 25, 1912. Mr. 

 W, B. Stokes (Hon. Sec.) contriljuted a paper " On Eesolutions obtained 

 with Dark-ground Illumination, and their Relation to the Spectrum 

 Theory." A number of experiments were described, of which we may 

 select one. An objective of N.A. 0'86 and a dark-ground illuminator 

 of N.A. 1 • 35 were employed. According to the Abbe theory, this should 

 resolve 58,750 lines per inch, using light of wave-length 5080. In 

 practice it was found that this combination would resolve the 60,000- 

 band of a Grayson's ruling ; it was therefore suggested that we should 

 be justified in turning for guidance to the older theory of Airy. Mr. 

 R. W. H. Row, B.Sc, reported the occurrence in large numbers, at 

 Maiden Railway Station, Surrey, of a rare saw-fly of the genus Phyllotoma 

 (possibly P. aneris). 



DiEEKs, W. — Einfiihrung in das Mikroskopieren Union, Deutsclie Verlagsgesell- 

 schaft. Berlin: (1912) 122 pp. (34 figs.). 



Heine MANN, P. G. — A Laboratory Guide in Bacteriology, for the TJse of Students, 

 Teachers, and Practitioners. 



Chicago : University Press, 2ncl ed. (1911) 88 pp. 



