ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 107 



celloidin as albumen dissolves neutralised. For histological staining of 

 the sections, the following solution is used : water 100 c.cm., hematoxylin 

 1 grin., chloral hydrate 7-9 grm., 50 p.c. acid molybdate of ammonia 

 20-30 drops. The mixture is exposed to the light for 8-10 days. The 

 sections stain in a few seconds. 



Staining Axis-Cylinders with Carmin.* — E. Chilesotti describes 

 the following method for staining axis-cylinders. (1) Fixation, Midler's 

 fluid for 4 months or more, or formol-Muller (1-10), or formol (about 

 1 p.c.) for 4 days at least. (2) Impregnation (only for pieces fixed in 

 formol or in formol-Muller) in Weigert's solution for staining medullary 

 sheaths. (3) Imbedding in celloidin. (4) Sectioning. (5) Staining. 

 The staining solution is made by boiling for half-an-hour 1 grm. of 

 carmin nacarat (Merck) finely powdered, in about 250 c.cm. of tap-i 

 water. After standing for 24 hours, the clear fluid is decanted off and 

 then is added one drop of an alcoholic solution (70°) of hydrochloric 

 .acid (1 p.c.) to each c.cm. of aqueous carmin (3 c.cm. to 100 c.cm.). The 

 mixture is then briskly shaken twice at intervals of 5 minutes. After 

 standing for 24 hours the clear fluid is decanted off. Thymol 1-1000 

 is added to prevent mould. The sections remain at least 20 hours in 

 the staining solution, and on removal are washed in distilled water. 

 (6) Differentiation. The sections are immersed for ?>0 seconds in an 

 aqueous solution of permanganate of potash 1-2500 (i.e. 5 parts of 

 water and 1 part of \ p.c. of Pal's solution). They are then transferred 

 for 10-60 seconds to a saturated aqueous solution of sulphurous acid 

 {S0 2 5 p.c). Wash in water and repeat the procedure, diminishing the 

 stay in permanganate, until the section is of a rose colour traversed by 

 reddish lines. Finally, 96 p.c. alcohol, carbol- xylol, Canada balsam. 



The axis-cylinders and the ganglion-cells are stained red while the 

 neuroglia and the medullary sheaths are quite decolorised. The red 

 •corpuscles, the nuclei of the neuroglia, are partially stained. 



The author calls the attention of microscopists to this selective 

 staining by means of carmin, a pigment which has been much neglected 

 in recent times. 



Staining and Preservation of Series of Sections on Paper Slips.f 

 A. Schoenemann, after mentioning the material worked with (nasal 

 cavity of infants, petrous bone of adults), describes the method of de- 

 calcifying. At first 7 p.c. sulphuric acid was used, but afterwards 

 sulphurous acid. The material was immersed in a saturated solution, 

 and as long as it remained therein, remained hard, but on being trans- 

 ferred to water the bone salts dissolved out. After dehydration in 

 absolute alcohol, the objects were transferred to a mixture of ether and 

 •oil of cloves (2-1), and then to Stepahow's celloidin, which consists of 

 celloidin chips 1 • 5 grm., oil of cloves 5 grm., ether 20 grm., absolute 

 alcohol 1 grm. 



After a time, varying according to the size of the object, they were 

 •covered with chloroform, and when sufficiently hard the paper casing was 

 stripped off and the mass placed in chloroform. When the hardening 

 is complete the blocks are transferred to cedar-wood oil if they are to 



* Zeitechr. f. wiss. Mikr., six. (1902) pp. 161-76. t Tom. cit., pp. 150-61. 



