ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 535 



Marking Paraffin Blocks.* — W. H. Harvey describes a new method 

 of marking" paraffin blocks for purposes of orientation or identification. 

 It consists in embedding in the same block as the tissue a thin pencil of 

 coloured paraffin-wax, having a melting-point somewhat higher than 

 that of the embedding mass. While the mass is molten, a length of 

 coloured wax pencil, sufficiently long to project above the block moulds, 

 is placed vertically in the liquid wax in any desired relation to the 

 tissue. A clear and definite mark thus persists throughout the Ijlock. 

 Such a means of orientation is particularly useful as a reconstruction 

 guide in embryological investigations. 



To make the wax pencils, paraffin of a melting-point 10° C. higher 

 than that of the paraffin oven is drawn into lengths of glass tubing of 

 0*5-1 mm. in diameter. The inner surface of the glass is first of all 

 thinly coated with oil to prevent the wax from sticking. The tubes 

 when full of wax are allowed to cool, file-marked, and carefully cracked. 

 The pencil may be drawn out of the tubing, and kept ready for use. 

 Of the available pigments, some such as congo-red may be added directly 

 to the wax, while others must first be dissolved in melted stearic acid. 



(4; Staining- and Injecting. 



New Staining Method for Biliary Canaliculi.t — B.M. Vance states 

 that the bile canaliculi are brought out as fine dark blue or black double 

 lines, outlined against the lighter blue of the liver cells, by the following 

 method. Fix in equal parts of Zenker's fluid, without the acetic acid, 

 and 10 p.c. formalin, or in equal parts of 10 p.c. formalin and 5 p.c. 

 sublimate. After hardening, embed in celloidin and place the sections 

 in a dilute solution of iodine in 96 p.c. alcohol for 5 to 15 minutes. 

 Wash thoroughly in 95 p.c. alcohol to remove iodine. Stain with 

 phosphotungstic-acid-hfematoxylin (Mallory) for 12 to 24 hours. Wash 

 in 95 p.c. alcohol. Clear in carbol-xylol and mount in balsam. 



Formula for the Chrom-osmic-acetic Acid Fluid. f — F. Zieglwallner 

 remarks in connexion with his article on the fixation and staining of 

 glycogen and its demonstration together with fat, that a convenient 

 formula for the alcoholic chrom-osmic-acetic acid mixture is the follow- 

 ing : 10 p.c. chromic acid solution in distilled water, 1*5 c.cm. ; 2 p.c. 

 osmic acid solution in distilled water, 4 c.cm. ; acetic acid, 1 c.cm. ; 

 alcohol (75 p.c), 1:')'5 c.cm. 



Demonstrating Spirochgsta pallida. § — C. Levaditi was successful 

 in demonstrating S. jmlUda in about 9() p.c. of the cases examined. 

 The procedure adopted was to take a small piece of the cortex cerebri 

 (2-3 mm.) and tease it out in 2 or 3 drops of saline. Smears were then 

 examined by Burri's Indian ink method, by staining by the Fontana- 



* Y. Path, and Bact., xviii. (1913) pp. 8-10. 



t Anat. Anzeig., xliv. (1913) pp. 412-13. 



i Zeftschr. wiss. Mikrosk., xxx. (1913) p. 72. 



§ Ann. Inst. Pasteur, xxvii. (1913) pp. 577-96 (1 pi.). 



