84 NOTES AND MEMORANDA. 



of fact with reference to the particular experiments now under consi- 

 deration, has been publicly questioned. I myself doubted it, and ex- 

 pressed my doubts, if not publicly, at least in conversation. I am 

 content to have established — at all events to my own satisfaction — 

 that, by following Dr. Bastian's directions, infusions can be prepared 

 which are not deprived, by an ebullition of from five to ten minutes, of 

 the faculty of undergoing those chemical changes which are charac- 

 terized by the presence of swarms of Bacteria, and that the develop- 

 ment of these organisms can proceed with the greatest activity in 

 hermetically-sealed glass vessels, from which almost the whole of the 

 air has been expelled by boiling." 



NOTES AND MEMOKANDA. 



Monochromatic Sunlight, by means of Glass Plates. — In a 

 recent number of the ' American Naturalist ' it is stated that Mr. J. 

 Edwards Smith, of Ashtabula, Ohio, has obtained light with which he 

 is perfectly satisfied, by means of a light sky-blue and darker green 

 glasses. He prefers to use one blue glass combined with two or three 

 green ones, the best shades being ascertained by trial. Several such 

 sets, of different depths of colour, may be mounted in a series, like 

 magic-lantern pictures, so that either set can be brought easily over 

 the hole in the shutter. By sunlight transmitted through such a 

 combination of glasses, and without condenser or apparatus of any 

 other kind, he " resolves " all the shells of the Probe Platte with per- 

 fect ease. He considers the light thus modified as good as the more 

 nearly monochromatic light of the troublesome ammonia-sulphate 

 cells. 



An interesting paper on the Thysanuradae is contributed by one 

 of our Fellows, Mr. S. J. M'Intire, to ' Science Gossip ' for December. 

 We refer those of our readers who are anxious to know where they 

 may obtain scales, to the paper itself, which describes many species of 

 these animals. 



Mr. Powell's -£„ Objective. — This is described by a contributor to 

 ' Science Gossip ' (December) in the following terms, which we think a 

 little too flattering, though the glass is certainly a wonderful piece of 

 mechanism and the definition remarkably good: — It appeared to per- 

 form well, defining the Podura test sharply and without colour, and 

 having plenty of light. Its magnifying power is 4000 diameters with 

 the A eye-piece, with an angular aperture of 160°; it bears the B and 

 C eye-pieces, with no other detriment than some loss of light, and 

 works well through covering glass ■ 003 thick. 



The Use of Glycerine in Microscopy. — Dr. Woodward replies 

 to the remarks of Dr. Beale in the last number of the ' Lens.' He says 

 (among other things) that as the climate of England is not subject to the 



