ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 559 



These are allowed to act for some hours with a small quantity of 

 water, and 100 grms. of pure water are then added. Filter. 



h. Bed. Dissolve 0-50 egrm. of alum in 10 grms. of water, and 

 add 0*50 cgrm. of saffranin dissolved in 10 grms. of pure alcohol. 

 Filter. 



The objects or sections are washed in distilled water and placed 

 in the blue solution for 5-10 minutes. They are then washed in a 

 large quantity of pure water and placed in the red solution for 

 5-10 minutes. 



Before staining intestinal worms they are rendered transparent 

 by a mixture of acetic acid and glycerin. 



Staining Tissues for Photo-micrography.* — Hsematoxylin stain- 

 ings in very thin sections, while all that can be desired under 

 the Microscope, are usually very disappointing when photographed ; 

 the delicate layer of tissue offers almost no actinic contrast when 

 monochromatic sunlight is obtained by the ammonio-sulphate of 

 copper cell. Since hsematoxylin is so extensively employed, a 

 ready modification to meet the needs of photography is of advantage, 

 and the following is suggested by Dr. G. A. Piersol. While 

 especially intended for nervous tissues it produces specimens 

 of all organs admirably adapted for photography. No especial 

 formula for hematoxylin is needed, using one which is capable of 

 staining deeply and giving standard results. In the usual course 

 of work the sections are stained ; a very few thin ones, however, are 

 allowed to remain in the solution, after those for ordinary preparation, 

 until they are of an intense dark purple, when they are transferred, 

 one by one, to a capsule containing a solution of borax 1*0; potas- 

 sium ferri cyanide 2-5; water 100 -0. In this they are kept moving 

 until the intense colour is gradually discharged, and the purple tint 

 is replaced by a bronze-yellow, shading to saffron. Before the sec- 

 tions reach the latter colour they should be washed in water ; the 

 further usual steps in mounting are then completed. 



Sections so stained, and mounted in balsam, will be found to 

 possess all the differentiation given by hsematoxylin, with a change 

 from the purplish blue colour to the subdued tones of brown — a 

 substitution often most pleasing and grateful to the eye. 



Collodion and Phenol in Microscopical Technique.t — Dr. 

 Bergonzini transfers sections which have been made from prepara- 

 tions hardened in alcohol or other reagent, and stained or not, from 

 water into phenol (in which they become transparent) and mounts in 

 a suitable medium. The specimen has not to be dehydrated as in 

 other methods. The action of the phenol can be hastened by gently 

 warming it. Pure phenol is iised, to which only as much water is 

 added as will dissolve it. Some recommend the employment of 

 phenol and alcohol in equal parts. 



Small animals, e. g. Insecta, can be placed alive in the phenol, 

 which kills and renders them transparent. 



* Amer. Mon. Micr. Journ., vi. (1885) p. 41-2. 

 t Lo Spallanzani, 1883, p. 196. 



