226 THE MICROSCOPIST. 



Place a piece of human scalp, skin from palmar surface 

 of finger, and skin of dog (for muscles of hair-follicles) in 

 chromic and spirit fluid. In a month transfer to methy- 

 lated spirit. 



Remove the petrous portion of temporal bone, open the 

 tympanum, pull the stapes from the oval fenestra, and place 

 the cochlea in chromic and spirit fluid. Change in eighteen 

 hours, and at the end of seven days, if a brown precipi- 

 tate falls, change fluid every third day. On the tenth or 

 twelfth day transfer to chromic and nitric fluid. Change 

 frequently till the bone is soft. Then place it in methy- 

 lated spirit. The cochlea of the guinea pig projects into 

 the tympanum, and is, therefore, convenient for enabling 

 the student to see how the cone is to be sliced when sec- 

 tions are made. 



Too long exposure to chromic acid renders tissues friable, 

 and prevents staining with carmine. 



Methylated spirit is ordinary alcohol containing 10 per 

 cent, of wood-naphtha, and is used in England as a substi- 

 tute for alcohol, since it is free of duty for manufacturing 

 purposes. 



CHAPTER XIII. 



THE MICROSCOPE IN PATHOLOGY AND PRACTICAL MEDICINE. 



PATHOLOGICAL HISTOLOGY, though yet imperfect, has at- 

 tained an extended literature. Paget, Jones, Sieveking, 

 Rokitansky, Virchow, Rindfleisch, and Bill roth are names 

 of investigators in this department, well known to medi- 

 cal students. As in our former chapters, we aim only to 

 present the briefest and most elementary outline of the 

 subject as introductory to more extended research. 



