ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 313 



bichromate of potash solution. AVhen ready it is embedded and sections 

 made. The sections are placed for three days in 2*5 p.c. potassium 

 bichromate. After a wash in water they are stained for 12 to 24 hours 

 in hematoxylin (10 parts of 10 p.c. alcoholic solution of ha3niatoxylin to 

 90 parts water). After a wash in water they are treated with a freshly- 

 made mixture of a 2 p.c. solution of red prussiate of potash, 10 parts ; 

 saturated aqueous solution of lithium carbonate, 30 parts. This pre- 

 liminary differentiation is finished when the edge of the celloidin is 

 decolorized (about 1 minute). After a thorough wash the sections are 

 treated with 2*5 p.c. potassium bichromate for 30 seconds. After 

 another wash the sections are further differentiated by Pal's method 

 as follows : 30 to 60 seconds in 1 : 600 potassium permanganate, wash, 

 and then bleach in a recently-made mixture composed of 1 p.c. oxalic 

 acid, and 1 p.c. sulphate of soda, in equal parts. The differentiation 

 is repeated until the tone is whitish throughout. The sections are 

 darkened by immersion in ammonia or lithia- water. 



Demonstrating the Structure and Innervation of Dentine.* — The 

 material used by C. Fritsch consisted chiefly of normal human teeth 

 and also some from the calf, dog, and hedgehog. The teeth were 

 preserved in' formalin for at least 4 weeks, and were then decalcified 

 by Schaffer's method, f Sections were prepared by the freezing method. 

 For staining the nerves a modification of the Bielschowsky procedure 

 was adopted^ The sections were taken from distilled water and 

 placed in pyridin for 24 hours. They were then transferred to distilled 

 water, frequently changed, for 24 hours. After this the sections were 

 placed for 5 to 8 days in 3 to 5 p.c. silver nitrate, and then after a 

 short wash were immersed in the following ammonia-silver oxide solu- 

 tion. To 5 c.cm. of 20 p.c. silver nitrate, 5 drops of 40 p.c. caustic 

 soda were added. The resulting precipitate is then cleared up by 

 adding, drop by drop, pure ammonia. This ammoniacal silver solution 

 was then made up to four times its volume with distilled water, and 

 into this solution the sections were placed for 4 to 5 minutes. After 

 reduction with 20 p.c. formalin they were treated with distilled water 

 acidified with 1 drop of acetic acid. After washing with distilled 

 water the process was repeated, the best results being obtained after a 

 repetition of ten to twelve times. After being gilded the sections are 

 placed in a solution of gelatin, transferred to a slide, and then covered 

 with gelatin. The slides dry in about 24 hours, and can then be 

 examined with an oil-immersion. The gelatin solution is prepared by 

 dissolving 10 grm. of pure gelatin in 100 distilled water, then liquefy- 

 ing in a water-bath at 50° and filtering in an incubator. 



Demonstrating Elastic Fibres. § — L. Liperovsky demonstrated 

 the presence of elastic fibres in the human mammary gland at ages of 

 15, 18, 20, 39, 42, 68, and 70 years, by the following procedure. The 



* Arch. Mikr. Anal., lxsxiv. (1915) pp. 307-20 (2 pis.). 



t See this Journal, 1903, p. 558. 



J See this Journal, 1906, p. 735 ; 1907, p. 498 ; 1910, p. 670. 



§ Anat. Anzeig., xlv. (1914) pp. 504-11 (7 figs.). 



June 17th 19 H Y 



