ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 235 



(3) Illuminating and other Apparatus. 



Artificial Daylight for the Microscope.* — During the last two 

 years H. P. Gage, working in the laboratories of the Corning Glass- 

 works, has developed a glass filter which renders the light from a 

 nitrogen-filled tungsten lamp almost exactly like daylight. A.n energy- 

 diagram of the tungsten lamp shows very great divergences from that 

 of the solar spectrum, especially in the green, yellow and red ; but when, 

 the tungsten-lamp light is passed through the author's glass (Daylight 

 glass, G. 172 cJ)) the curve approximates very closely to that for 

 sunlight, especially between wave-lengths 0'45/x, and 0'6o /jl — i.e. in the 

 region of the visible spectrum giving the greatest amount of useful 

 light. The light filtered through the daylight glass has been very 

 critically tested in the author's laboratory on microscopic objects stained 

 with many different dyes, some of them even with several dyes on the 

 same specimen. To make sure that the Microscope itself in no way 

 modified the colour values apochromatic objectives and compensation 

 oculars were used, as well as the achromatic objectives and Huyghenian 

 oculars. The experiments were conducted near to a window so that 

 comparison with actual daylight could be readily obtained. The author 

 states that it was impossible to detect any difference between the 

 artificial and the natural effects. In practice it was found desirable to 

 have the daylight glass finished with the ground or velvet surface on 

 one or both sides, and to place it in the opening of an opaque screen 

 between the artificial light and the Microscope. With this arrange- 

 ment of the light the effect is like that from a white cloud. 



B. Technique.! ' 

 (1) Collecting Objects, including: Culture Processes. 



Cultivation of Plasmodia of Badhamia utricularis.| — In con- 

 tinuation of previous notes § on artificial feeding of plasmodia of this 

 species A. E. Hilton reports |j that plasmodia cultivated on bread and 

 water, with the addition of a mixture of ammonium and calcium phos- 

 phates and cane sugar, formed spores in due course. A growth was 

 started on Feb. 19th last year by reviving a fragment of sclerotium. 

 For some weeks, owing to low temperatures, development was slow ; but 

 on the weather becoming warmer, it increased considerably ; and on 

 j\Iay 5th, when the atmosphere became close, with a thunderstorm 

 impending, the plasmodia changed into a quantity of sporangia. There 

 were, however, striking differences between these sporangia and those 

 produced in natural conditions. They were similar in shape, but instead 

 of being of the usual cinereous hue, they were mostly a dark purple 



* Science, n.s. xlii. (1915) pp. 534-6 (1 fig.). 



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. t See also this Journal, 1915, p. 191. 



§ Journ. Quekett Micr. Club, 1914, xii. 381. 

 li Journ. Quekett Micr. Club, 1915, p. 585. 



