760 HISTOLOGIC TECHNIC 



3. Pass through graded alcohols to distilled water. 



4. Transfer to solution of 1 gram hemalum (Griibler's) to 10 c.c. 

 water, where it remains for eight to ten days. 



5. Wash in distilled water, embed in paraffin, and section. 



The intercalated disks are conspicuously stained a dark blue, which 

 contrasts sharply with the light-blue background. 



These disks can be well demonstrated also by fixation in Carnoy's 

 fluid, followed by iron-hematoxylin stain. For the same purpose Heiden- 

 hain employs vanadium hematoxylin after sublimate fixation (see Lee's 

 Vade Mecum). 



Gage's Method, for Demonstrating Glycogen. Glycogen granules 

 are readily soluble in aqueous media. Tissue which is to be tested for 

 this substance should be fixed in 95 per cent, alcohol. 



1. Embed in paraffin in the usual way. 



2. Flatten sections on slide by use of the following iodin solution 



(Lugol's solution), which is subsequently used for staining: 



Iodin 1.5 grm. 



Potassium iodid 3.0 grm. 



Sodium chlorid 1.5 grm. 



50 per cent, alcohol 300 c.c. 



3. Stain, dehydrate, dissolve paraffin with xylol, mounted in melted 



vaselin, and seal cover glass with shellac. The glycogen grains 

 are stained mahogany red. 



Osmic Acid Technic for Fat. Free fats and lipoids are soluble in 

 ether, chloroform, absolute alcohol, xylol, benzene, and essential oils. 

 Since these must be employed in both paraffin and celloidin embedding, 

 fat cannot be very satisfactorily demonstrated by these technics. Frozen 

 sections (made with a freezing microtome) of fresh or formalin-fixed 

 tissues are therefore preferable (in some instances indispensable) ; these 

 may be satisfactorily stained with Sudan III (red), Sharlach E (red), 

 Nile blue (blue) ; they must be mounted in glycerin jelly. 



Osmic acid, however, renders certain fats resistant to solution in 

 oils, and tissue so fixed may accordingly be treated by the paraffin tech- 

 nic; but thick cedar oil must be substituted for xylol or chloroform, and 

 absolute alcohol should be avoided: 



1. Fix small pieces of fatty tissue in Flemming's fluid for two days. 

 <?. (a) Embed in paraffin (use cedar oil), section, and mount in 

 euparal; or 



