NOTES AND MEMORANDA. 473 



President, Miss Cook, was in the chair. Miss Dickinson read a paper 

 upon animal and vegetable hairs, which was illustrated by slides of 

 horizontal sections of the scalp prepared by Miss Nunn, Professor of 

 Biology ; Miss JBeattie presented a i^aper on Bacteria ; Miss Whipple 

 gave a demonstration of the method of cutting and double staining 

 vegetable sections, beginning by describing the proper method of 

 honing a razor ; slides mounted by Misses Cummings and Whipple 

 were exhibited ; Miss Whiting called attention to the receipt of fifty 

 of Smith's slides of Diatomacefc ; and, finally, the report is attested 

 by " Marion Metcalf, Corresponding Secretary." 



Oblique lUumination. — Mr. C. Hue says that he has obtained 

 highly successful results where extreme obliquity of illumination is 

 required, by the use of the parabolic illuminator, in conjunction with 

 a small super-stage, similar to that of Dr. Matthews. 



Limits of Accuracy in Measurements with the Microscope.— 



Professor Eogers calls attention to the note on p. 345 of vol. i., and 

 says that the error referred to consists in the report from which wo 

 quoted having given 32 millionths instead of 32 ten-milliouths. 



Royal Society Conversazione. — On April 30th, at the above Con- 

 versazione, the following were the exhibits relating to microscopy : — 



Messrs. Powell and Lealand : — Their new ^ oil-immersion lens, 

 with P. angulatum. 



Mr. F. Ward : — New micro-spectroscope, in which a rectangular 

 quartz prism is substituted for the usual metallic slit, (This Journal, 

 vol. i. p. 326.) 



Mr. J. Mayall, jun. : — Zeiss's new y^^ oil-immersion lens, with 

 Amj)hipleura pellucida (in balsam) ; and the improved immersion 

 illuminator designed by the exhibitor with special reference to the 

 Eoss-Zentmayer stand. 



Mr. Crisp : — Powell and Lealand's new ^ oil-immersion lens, with 

 Frustulia Saxonica (dry), and a similar illuminator. 



