ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 703 



that fixing and staining reagents cannot be mixed indiscriminately. In 

 the first place the optimum reaction of the various substances must not 

 be disturbed, and, further, there are differences in activity, time of action 

 and so on, which have to be considered. Some stains and fixing reagents 

 are not miscible. For fixing and staining 1 train-tissues, the author re- 

 commends a mixture of 10 p.c formalin and Ehrlich's tri-acid stain. 

 This solution is also applicable to liver, kidney, spleen, and other tissues. 

 Good results have also followed the use of a formalin-toluidin-blue 

 mixture — 10 p.c. formalin 100 parts, toluidin blue (solid) 3 parts. 



Preparation of Kaiserling Material for Microscopical Purposes.* — 

 B. Rawitz has devised the following method. Portions of tissue prepared 

 by Kaiserling's method are put into 95 p.c. alcohol containing 10 p.c. 

 tincture of iodine for fourteen days. The fluid is changed every day for 

 the first three days, as it becomes turbid ; after this time it will remain 

 clear. From the iodine solution the material is transferred to a saturated 

 potassium bichromate solution for fourteen days, the fluid being changed 

 twice. The material is lightly blotted with filter-paper and put into 

 95 p.c. alcohol for two days, absolute alcohol for two days, and chloro- 

 form for a like period. From this it is transferred to chloroform-paraffin, 

 and finally embedded in paraffin. 



The author also describes the application of certain stains, formol- 

 f uchsin and azofuchsin, to the staining of nervous tissues. 



(3) Cutting-, including Embedding and Microtomes. 



Microtome Knives. — The firm of E. Leitz has recently completed 

 arrangements for the manufacture of microtome knives in Sheffield, and 

 are also prepared to undertake the re-sharpening of microtome knives. 

 The sizes of the knives are from 4f to H in. in length. 



Improvements in Rock-section Cutting Apparatus.! — H. J. Gray- 

 son thus describes the structural features of his new machine for cutting 

 rock-sections. 



" Dealing with the several portions of the machine in order, Plate 

 XX., which may be regarded as equivalent to a sectional or front 

 view, shows all the principal features of the apparatus, which is built 

 into a corner of the workroom ; the lathe in the foreground has no con- 

 nexion with the rock sheer, beyond being driven by the same motor. 

 The three guard-trays have been removed from the top of the rock 

 machine table, in order to show the position and relation of the slicing 

 and grinding-lap spindles, and of the several supports for rock-holder- 

 and clamps. 



Plate XXI. may be regarded as a photograph in plan, i.e. looking 

 down upon the machine. It shows to better advantage the relation of 

 the working parts in running order, other than the driving mechanism, 

 which is situated at some height above the machine, and is shown in 

 detail in Plate XXII. 



* Zeitschr. wiss. Mikrosk., xxviii. (1911) pp. 1-11. 



t Proc. Roy. Soc. Victoria, xxiii. (1910) pp. 65-81 (4 pis.). 



2 X 2 



