— 73 



Lesson XVIII. 

 SKIN AND APPENDAGES. 



(a) Macerated Epidermis. 



A small piece of skin was macerated for several clays in %% 

 solution of acetic acid. The epidermis was then carefully lifted 

 from the dermis, rinsed in water, hardened in alcohol, stained in 

 l)orax carmine, and cleared in oil of bergainot. Blount in balsam, 

 takin? care to mount it in such a way that the under surface of the 

 epidermis is uppermost. 



Study under low power. Observe the depressions in 

 the under surface of the epidermis into which the papilla? 

 of the true skin fit. Note their number and arrangement. 

 Sketch under low power. 



(b) Preparation of the Dermis. 



Tlie skin was macerated as above, and the epidermis removed. 

 The dermis was hardened in alcoliol, stained in borax carmine, em- 

 bedded in paratHn, and sectioned. 



Study under low power. This section is given to show 

 the papillffi of the true skin. In many of these a capil- 

 lary network can be made out. Sketch a number of the 

 papilla? under low power. 



(cj Cross-Section of Human Skin. 



A small piece of skin removed from the plantar surface of the 

 foot or palmar surface of the hand was hardened in 10% nitric acid 

 for 24 hours, then in Milller's fluid for two weeks, stained in Dela- 

 field's luiematoxylin, embedded in paraffin, sectioned, fixed to cover 

 glasses, counter-stained in 1% acid fuchsin, dehydrated, and cleared 

 in oil of bergamot and xylol. Mount in balsam. 



This section is to be studied first under low power, and 

 the general arrangement of the tissues observed. In the 

 epidermis the following layers are found, named in order 

 from within, outward: — 



