ZOOLOGY AND BOTANY, MICKOSCOPY, KTO. 813 



Weight, L. — Micro-photography. 



[Reply to inquiry as to photographing diatoms aud diffraction-gratinga. 

 Also reply by S. Bottone.] 



Engl. Mech., XXXIX. (1884) pp. 519-20. 

 Zenger, C. V. — Detemiination des Indices de Re'fraction par des Mesures 

 lineaires. (Determination of indices of refraction by linear measures.) 



[Simple method of strict determination to the 5th decimal by means of a 

 divided rule with a small telescope sliding on the alidade which carries 

 the vernier.] 



Comptes Bendus, XCIX. (1884) pp. 377-80. 



3- Collecting', Mounting and Examining Objects, &c. 



Killing Infusoria.*— J. P. McMurrich finds that for killing 

 infusoria, provided only a temporary preparation is required, a 

 saturated solution of corrosive sublimate in water is the most useful 

 he has tried. A drop or two run under the cover-glass produces 

 almost instant death without any of the shrinkage so annoying even 

 with osmic acid. After this treatment staining with anilin blue, 

 black, or Brunswick brown takes place very rapidly and very 

 satisfactorily. 



PercMoride of Iron.f — H. Fol has overcome some of the incon- 

 veniences of this reagent and has made it " really practical." The 

 iron salt may be completely extracted from a preparation fixed by 

 being for 1/2-1 hour in the perchloride, diluted with alcohol, by 

 washing with an aqueous solution of oxalate of potash, or an alcoholic 

 solution of oxalic acid. The tissues can then be preserved in weak 

 alcohol and stained with success by the ordinary process, using 

 carmine, haematoxylin, and anilin dyes. 



The author adds " These preparations are only distinguishable 

 from those obtained by the usual fixing agents by the extraordinarily 

 faithful preservation of the vibratile cilia, the pseudopodia, and the 

 nuclear filaments." 



Mounting of Foraminifera— New Slide for Opaque Objects.}: — 

 Dr. F. M. HamliQ considers that for the finest forms, and for cal- 

 careous sands, such as the famed Bermuda sand, there is no plan so 

 satisfactory as to search through the material with the Microscope, to 

 save time and labour separating the sand into grades by passing it 

 through sieves of thi-ee dift'erent degrees of fineness. The shells from 

 the last will exercise the skill nearly as much as diatoms. Having 

 sifted the sand, it should be examined on a specially devised slide, 

 made as follows; — A piece of jjasteboard the size of an ordinary slide 

 has a long slit cut in it, and is then fastened to a glass slide. The 

 width of this slip is of importance, aud is determined thus : Tako 

 a low power objective, say a three or four inch, which aftbrds just 

 sufficient power to see the shells well, and measure the width of its 

 field. Make the slit or opening in the pasteboard just twice this 

 distance. The slide being ready, a little pinch of sand is put on the 

 glass, and a slight shake spreads it out in a single layer confined by 



* Amer. Natural., xvlii. (1884) p. 832. 



t Arch. Zool. Exper. ct Gen., ii. (1884) p. ix. 



X Proc. Auicr. Hoc. Micr., 6th Anu. Meet., 1883, pp. C5-8. 



