ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 115 



The author also mentions that the foregoing fixation is suitable for 

 iron-hfematoxylin staining. The sections, made by freezing microtome, 

 are immersed for 2-5 hours in 2 p.c. iron-alum solution, and having 

 been washed in water, are placed for 10-12 hours iu ^ p.c. aqueous 

 solution of hematoxylin. They are next differentiated in 2 p.c. iron- 

 silum solution (from 1-3 hours). The medullary sheath of the nerves is 

 dark blue, the rest of the tissue being unstained. The sections are theu 

 washed very thoroughly (several hours), and afterwards mounted in the 

 usual way in balsam. 



(5) Mounting-, including- Slides, Preservative Fluids, &c. 



Examination of Hairs for Medico-legal Purposes.* — E. S. London 

 states that hairs intended for medico-legal examination should be mounted 

 dry in balsam without any preliminary preparation or treatment, as 

 reagents cause them to lose many of their characteristic features. From 

 many thousand examinations of hairs of man and of animals (39 species) 

 he comes to the following conclusions. By the use of the Microscope it 

 is easy to distinguish the hair of man and of animals from any body or 

 substance of a similar appearance. With a little practice it becomes easy 

 to discriminate between human hair and that of the lower animals ; 

 and if all the peculiarities be taken into consideration the original site 

 of a hair may be diagnosed. From the appearance presented by the 

 roots it is possible, if several specimens be available, to determine 

 whether the hairs have fallen out naturally or have been plucked out. 

 By means of the polariscope a grey hair can be diagnosed from a pale 

 blond. With crossed nicols blond hair gives a golden yellow band on a 

 black ground, while grey hair gives a particoloured band (cordon), the 

 red-purple predominating. 



In arsenic poisoning the metal passes into the hair. This was shown 

 by injecting arsenic solution into animals hypodermically and testing 

 the hair by the usual chemical methods. The control animals gave a 

 negative result. 



Substitute for Cover-slips.f — Dr. V. Pranter recommends gelatin- 

 paper as a substitute for the more expensive glass slips of large size. 

 The paper consists of pure gelatin, is almost colourless, perfectly trans- 

 parent and smooth. It can be used with advantage for all preparations 

 which do not contain, or are not mounted in water or glycerin. It 

 allows examination under oil immersions. Though less suitable than 

 glass for permanent preparations, the specimens will keep for months 

 without deterioration provided they be stored in a cool, dry place. 

 Dirt or grease on the surface is easily removed by means of xylol or 

 benzin. 



Preparation and Preservation of Urinary Sediment.^ — Gr. Marp- 

 niann prepares and preserves urinary sediment as follows : — Some 100 to 

 200 ccm. of urine are placed in a conical vessel, and when a sediment 

 of, say, 20 ccm. has been deposited the supernatant fluid is decanted off. 

 To the sediment 1 ccm. of eosin and 1 ccm. of methylcn-blue in aqueous 



* Archiv. Sci. biolojaque St. Petersb., viii. (1900) pp. 136-57 (6 pis.), 

 t Zeitschr. f. wiss. Mikr., x.viii. (1901) pp. 159-61. 

 j Zeitschr. f. angew. Mikr., vii. (1901) pp. 182-4. 



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