ZOOLOGY AND BOTANY, MIOROSOOPY, ETC. 151 



The pigments are first rubbed up with spirit, and having been 

 filtered through gauze, added in the desired proportion to the shellac 

 solution. In 10-12 minutes the injected mass is hard. Syringe and 

 canula must be immersed in spirit previously and carefully washed 

 therewith after injection. After injection the eyes are placed for 

 24- hours in 0*2-0 '3 per cent, chromic acid, and then having been 

 cleaned up with a brush, are washed in running water for 24 hours. 

 The thicker parts and those which retain the pigment are then macerated 

 in eau de Javelle for a longer or shorter time. If allowed to work too 

 long the macerating fluid destroys the walls of the vessels and renders 

 the preparation useless. It is then washed again in running water for 

 12 to 24 hours, and afterwards, having been mopped up with blotting- 

 paper, it is stretched between two slides and allowed to dry. 



Permanent preparations may be mounted dry and ringed round with 

 paraffin or some quick-drying varnish, or may be cleared up in turpen- 

 tine and mounted in balsam. 



Double injection gives very good results, the arteries with cinnabar 

 from the carotid, the veins with Berlin blue from the vense verticosge. 



Black Injection-mass.* — Prof. A. Letellier advocates the use of a 

 mixture of vanadate of ammonia and tannin as an injection-mass. The 

 advantages of this mixture are that it is black in itself, and does not 

 depend for its colour on solid particles in suspension ; that it has no 

 tendency to diffuse outside the vessels into the tissues ; that the mass 

 will pass through the finest canula and not block the point ; that the 

 walls of the vessels, even when not entirely filled, are stained black ; 

 and that when pieces of the injected tissue are placed in spirit the 

 colouring matter is not withdrawn, as vanadate of ammonia is insoluble 

 in alcohol. 



The preparation of this injection-mass is extremely simple. Vana- 

 date of ammonia is soluble in warm, and tannin in hot water. The two 

 solutions are kept apart until required for use, when they are mixed in 

 proportion to the tint required. 



For the tannin, pyrogallic acid or a solution of nut-galls, made by 

 macerating the bruised galls in cold water, may be substituted. 



Teclmique of the "Corrosion" of Celloidin Preparations.f— Dr. 



Bellarminow recommends that celloidin sections of the eye injected with 

 Berlin blue should be treated with eau de Javelle in order to destroy the 

 pigment which interferes with the examination. Thick sections are 

 placed for ten to thirty minutes in a solution of sodium carb., calcar. 

 chlor., 12 '5 each, water, 100 parts. Thinner sections in a weaker 

 solution. They are then washed in running water for twenty-four 

 hours. Then dehydration, clearing up, and Canada balsam. The 

 celloidin imbedding increases the resistance of the sections to the action 

 of eau de Javelle, consequently this reagent is very suitable for the 

 purpose. 



* Bull. Soc. Linn. Normandie, i. (1888) pp. 171-i. 

 t Anat. Anzeig., iii. (1888) pp. 650-1. 



