ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 779 



solution (1 p.c. safranin in absolute alcohol to which a few drops of 

 anilin-water have been added), diluted with an equal bulk of distilled 

 water. After frequent washings in distilled water, the sections are 

 placed in I p.c. aqueous solution of gentian-violet for 24 hours ; then, 

 after more washings in water, immersion in an aqueous solution of 

 orange G- for about one minute. The strength of this solution varies 

 with the object to be stained, and the result must be controlled under 

 the Microscope. The sections are next immersed in absolute alcohol to 

 which (» to 8 drops of a mixture of equal parts of absolute alcohol and 

 pure hydrochloric acid have been added ; they are removed directly 

 violet clouds are given off. Then absolute alcohol again to remove the 

 acid. The special differentiation is effected in oil of cloves, which may 

 be thinned down with a little absolute alcohol. This is a slow process, 

 and should be controlled under the Microscope, and is usually ended 

 when the nuclear portions are blue and the non-nuclear yellow. Then 

 pure oil of cloves ; then drain in vertical position on blotting-paper ; 

 xylol, xylol-balsam. 



The authors end their remarks by pointing out the importance of 

 using the best safranin, for if this pigment does not work well the violet 

 and orange also produce useless pictures. 



Localising Purin Bodies in Animal Tissues.* — C. Ciaccio demon- 

 strates the presence of purin bodies in the organs of Vertebrates under 

 normal and pathological conditions by the following method, the 

 technique of which depends on two principal facts, viz. the formation of 

 urate of silver, and the property possessed by purin bodies of reducing 

 ammoniacal solution of silver nitrate. Three forms of procedure are 

 given. 



1. To a l|-2 p.c. solution of silver nitrate is added ammonia drop 

 by drop, until the precipitate formed is dissolved. After filtration 

 ammonia is again added until the odour is clearly perceptible. The 

 filtrate, placed in a perfectly clean vessel, is kept in the dark. In this 

 solution small pieces (4 or 5-100 c.cm.) are placed for from 1 to 5 days, 

 according to the temperature, the optimum being 37-40°. On removal 

 the pieces are placed in 1 p.c. ammonia for 24 hours, the fluid being 

 changed every 2 or 3 hours. They are next washed, and then passed 

 through upgraded alcohols to xylol and paraffin in the usual way. The 

 sections are stained with thionin, toluidin-blue, methylen-blue, or poly- 

 chrome blue, or with the author's eosin-orange-toluidin stain. Acids 

 and hematoxylin must be avoided. 



2. The material may be fixed in 96 p.c. or absolute alcohol, or in 

 Carnoy's fluid. If in alcohol the pieces must be small, and after fixation 

 soaked in water ; if in Carnoy's fluid, they must be treated afterwards 

 with alcohol and then water. In both cases the subsequent treatment 

 is the same as in procedure (1). , 



3. Fixation in alcohol or in Carnoy's fluid ; imbedding in paraffin. 

 The sections having been freed from paraffin are passed through down- 

 graded alcohols to distilled water (a few seconds). They are then 



* Anat. Anzeig., xxiii. (1908) pp. 298-320 (18 figs.). 



3 F 2 



