The staining of hard tissues with silver

During a survey of “on-the-slide ” silver determine which might be the more suitable for a projected study sonie examples of specific staining of various cleineiits of hard tissues were found. These have proved valuable for teaching purposes as they make prominent details of structure somewhat difficult to see in routine preparations. Bone and tecth have been studied. In the latter, only ra t material has been used but consistent results in the staining of bone have been obtained with rat, rabbit and dog femurs. A number of #different fixatives, decalcifying agents and staining procednrcs were tried but for each clement only the most successful technic need be mentioned. Fo r the rat teeth the most satisfactory fixative has been 10% formalin with 1Ogm of chloral, hydrate addcd to each 1O8cm3 followed by decalcification in a formic acid sodium citrate mixture (Evxns and Krajian, ’30). Ponsistcnt results have been obtained with fixation of bone in a modified Rouin’s (saturated aqueoiis picric acid 75 em3, formalin [37%] 25 em3 and trichloracetic acid 1 gn) followed by decalcification in 5% trichloracctic acid in 50% alcohol. The use of a mordant hpfore impregnation seems to promote a lighter background. After removal of the paraffin and rchydration the slides are placed in 1%