238 PRACTICAL HISTOLOGY. 



less readily than those which have simply heen 

 hardened in spirit. 



Preparations 4-6. The scrotum, and labia, and 

 the vagina, are prepared in the same way as the 

 skin (see p. 187). 



Preparation 7. The human uterus is best 

 hardened in the 2 per cent, bichromate of potash ; 

 its cavity should be freely laid open. In animals 

 (the rabbit, for instance), where it is more membra- 

 nous, the uterus and the upper part of the vagina 

 may be prepared together by distending them with 

 the spirit and J per cent, chromic acid mixture 

 through a canula tied into the lower part of the 

 vagina. The vagina is then tied, and the organs 

 are cut out and placed in a quantity of the solution ; 

 in twenty-four hours they are laid open and the 

 fluid renewed, and in another day or two are ready 

 to be put into spirit. The sections are stained with 

 logwood, and mounted in dammar. 



Preparation 8. Section of ovary. The ova- 

 ries are prepared by placing them with as little 

 handling as possible, so as to avoid rubbing off the 

 columnar epithelium which covers the surface in 

 per cent, chromic acid (whole if taken from a 

 email animal, such as a rabbit or cat; cut into two 

 or three pieces if from a larger one). In most of 

 the lower animals they must be sought much higher 

 in the abdomen than in the human female; in the 

 rabbit they occur as small elongated bodies, dotted 

 all over with little projections (the Graatian follicles), 

 and situated just below the kidneys. They are 

 left in the chromic solution for seven days, and then 

 placed in spirit, and in two or three days more are 

 ready for cutting. The hardening is effected still 

 more readily by using the chromic and spirit mix- 

 ture. The sections are to be stained in carmine 

 solution ; for logwood sometimes colors very deeply 

 the coagulated fluid in the Graafian follicles, so that 

 the epithelial contents are obscured ; this coloration 

 is probably owing to the presence of mucus (or rather 



