ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 427 



a fluid of the following composition : sublimate 4 grm., potassium bi- 

 chromate 2*5 grm., chloral hydrate 4 grm., water 100 c.cm. — the iodine 

 treatment may be carried out simultaneously with the removal of paraffin, 

 by placing the mounted paraffin sections in xylol saturated with iodine. 



Aceton-ether Method of Paraffin EmhechliiKj. — Tissue is removed from 

 water or weak alcohol, and placed in a fluid containing : acetone 2 parts, 

 ether 1 part, water 1 part. In this it remains for at least one hour 

 for each millimetre in the thickness of the tissue. Transfer to a mixture 

 of equal parts of acetone and ether saturated with paraffin. Then transfer 

 to paraffin. 



Simultaneous Polychrome Stain. — Saturated watery toluidin-blue, 

 with 3 p.c. formol, 12 parts ; alcohol 90 p.c, 8 parts ; acetone, 4 parts ; 

 saturated uaphthol-yellow, in alcohol 90 p.c, 2 parts ; saturated ery- 

 throsin pur., in alcohol 90 p.c, 3 parts. Mix in the above order. Add 

 5 to 10 parts of distilled water. Stand. Xo precipitate should appear, 

 and the fluid should be dark blue, with a violet shade after a few minutes. 



Adhesion of Sections to Slide. — When the paraffin sections are floating 

 in warm water, add 1 drop of cedar-wood oil. This spreads as a thin 

 film over the surface of the water. Sections mounted direct from this 

 fluid will adhere firmly. 



C3) Cutting-, including- Embedding- and Microtomes. 



Method of Handling and Preserving Celloidin Serial Sections.* 

 H. Richter makes use of shallow rectangular glass dishes, with well- 

 fitting lids. One side bears a distinguishing mark, so that the orien- 

 tation of the vessel and its contents is always known. A piece of 

 blotting-paper, cut to fit, is placed on the bottom of this vessel, and 

 moistened with 70 to 90 p.c. alcohol. The sections are transferred from 

 the knife to the surface of the wet blotting-paper, being arranged in 

 order. When this is finished, a piece of paraffin -paper — of a type used 

 in commerce by vendors of sugar or drugs — is placed over the sections. 

 The lid of the dish is put on, and the sections may be kept in this 

 condition until required. The paraffin-paper may with care be peeled off 

 the sections, and one or more be removed for mounting. When single 

 sections are removed, it is recommended that a small piece of paper 

 with the number of the section be placed in the position it occupied in 

 the dish. 



By this method it is easy to study isolated sections from a series at 

 leisure, without breaking the series. Moreover, a diversity of staining 

 methods can be practised upon neighbouring sections. 



Wiilfing's Rock-slicing Microtome. f — This piece of apparatus has 

 been designed by E. A. Wiilfing, and is made by the firm of R. Winkel, 

 Gottingen. Its object is to make thin slices of large pieces of rock, 

 and to examine the qualitative orientation of mineral sections. 

 In the latter case it facilitates the necessary preparatory investigations 



* Zeitschr. wiss. Mikrosk., xxix. (1913) pp. 528-30. 



t Special Catalogue : Microscopes for Mineralogists ; Microtomes and Grind- 

 ing Apparatus Accessories. Carl Zeiss (Agents) London. 



