ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 873 



is sufficient to loosen the epidermis of the embryo. His experiments 

 have satisfied the author that a sojourn of several days in a • 6 per 

 cent, solution of common salt, with " 1 per cent, thymol added to 

 prevent putrefaction, is a simple and satisfactory way of liberating 

 the embryonic epidermis from its connections, so that pieces can be 

 easily removed for histological examination, for which they are 

 apparently still adapted; even the minute structure of the nucleus 

 will persist through this treatment, though imperfectly. 



Preparing Stratified Epithelia.* — Dr. G. Bizzozero proceeds to 

 the examination of fresh epithelial scrapings from inside the cheek, 

 by removing, first of all, other morphological elements in the following 

 manner : — 



Some saliva obtained by means of a pipette is transferred to three 

 or four times its bulk of a 0*75 per cent, solution of common salt. 

 The mixture is thoroughly stirred up and then allowed to stand. 

 When the epithelial cells have sunk to the bottom, forming a white 

 sediment there, the supernatant fluid is decanted off, and is replaced 

 by a fresh quantity of salt solution. This procedure having been 

 repeated three or four times the salt solution is replaced by dilute 

 alcohol in which the epithelial cells may remain unimpaired for a 

 length of time. In order to bring out quite clearly the linear 

 striation, some iodide of potash solution is added. 



Preparing Central Termination of Optic Nerves of Mammalia.! 

 Sig. T. Bellonci hardens the part of the brain to be examined in 

 osmic acid (^ to 1 per cent.) from 14 to 20 hours : then makes free- 

 hand sections in 70 per cent, alcohol, and then immerses for three or 

 four hours in 80 per cent, alcohol. After having been repeatedly 

 washed the sections are placed in water under a cover-glass, and some 

 ammonia is added. This makes the brain substance as transparent as 

 glass, with the exception of the medullated fibres, which remaining 

 black, stand out so clearly that it is easy to follow their course. 

 Thickish sections allow the course of the fibres to be followed for a 

 longer distance than thin ones. 



Preparing the Brain.J — Dr. J. Fischl would seem to have had 

 less encouraging results from Weigert's hematoxylin stain than other 

 observers. He found that ganglion cells gave the best results when 

 hardened in alcohol. The most advantageous stains were alum 

 carmine, borax carmine, hematoxylin, safranin, dahlia, and vesuvin. 

 Flemming's fixative fluid is much praised. The author has tried 

 Flesch's indigo carmine and borax carmine, but his results were not so 

 satisfactory as those from the foregoing methods. 



Examination of the Cerebral Cortex.§ — Dr. Nissl states that 

 isolation, without preceding maceration, may be carried out in any 

 indifferent fluid (maceration having no special significance in the study 



* Internat. Monatsschr. f. Anat. u. Histol., ii. (1885) pp. 278-83 (1 pi.), 

 t Arch. Ital. Biol., vi. (18S5) p. 405. 



j Prager Med. Wochensch., 188(5, No. 2, and Wiener Med. Wochenschr 

 188G, No. 5. Cf. ZeitBchr. f. Wiss. Mikr., iii. (1886) p. 100. 



§ Ber. Naturforschor-Yersammlung Strassburg, 1885, pp. 50(5 and 135. 



