Tlie Identification of Intracellular Structures. Ill 



tissue is left ia the reducing solution till a brown colour appears, 

 generally from one-half to one hour, 



5. Pass through upgraded alcohols to xylol and embed in 

 parafl&n. Sections on slide are brought into water and toned (if 

 necessary) in the following solution : — 



6. Toning. — {a) Sodium hyposulphite, 3 grm. ; ammonium 

 sulphocyanate, 3 grm. ; distilled water, 100 c.cm. (6) Gold chloride, 

 1 p.c. Use equal parts of («) and (h). Sections are toned for varying 

 times from about ten minutes to one-half hour, according to the 

 thickness of the sections. Dehydrate, clear and mount. 



As far as I can make out from preparations of Helix ovotestis 

 made by this method, the image given is generally very faithful, 

 though in other cases it is not limited strictly to the Golgi rod 

 itself, being diffuse, and the individual rods a solid mass. 



VII. Iodine Stain for Glijcogcn. — 1. fix tissues in 90-100 p.c. 

 alcohol. Lower strengths must be avoided. 



2. Prepare wax ov celloidin sections. Stain ten minutes in 

 Ehrlich's hsematoxylin. 



3. Pass sections to 1 p.c. solution of potassium iodide saturated 

 in iodine. Leave three to five minutes. 



4. Dehydrate in absolute alcohol saturated in iodine. Blot. 



5. Oil of origanum. Differentiate for at least ten minutes, till 

 the general diffuse iodine shade is somewhat extracted. 



6. Wash in xylol and mount in xylol balsam. (Oil of origanum 

 balsam has alsp been used, but this oil eventually destroys the 

 colour.) Such preparations will still show the iodine colour after 

 three years (placenta and liver). 



VIII. Intra-vitam Stains. — Besides the above methods, fresh 

 cells can be stained alive in neutral red about 1 in 20,000, in tap- 

 water or salt solution, and in Janus green about 1 in 30,000. 

 Both dyes stain the mitochondria clearly, and in male germ cells 

 generally the Golgi (nebenkern) elements as well. These methods 

 are valuable. 



IX. Toxic Stains for Fresh Cells.— Weak permanganate of 

 potassium (pink solution), one half p.c. OsOi, and osmic acid 

 mixed with certain weak dyes, such as methyl-green or dahlia, will 

 kill and stain freshly smeared cells. The mitochondria, and some- 

 times the Golgi apparatus, may show very clearly. 



Sections VIII. and IX. are useful for Protozoa and smears of 

 insect testes. The best results are gained by trying differing 

 strengths till the optimum is obtained. 



The Osmium Tetroxide and Silver-Niteate Eeactions 

 FOR THE Golgi Apparatus. 



Kopsch's method turns Golgi batonettes or granules, fat, and 

 often yolk, quite black; but it is easy to distinguish between 



I 2 



