XXIX.] THE NAILS. 327 



(3.) Extract (5-15 sees.) with official perchloride of iron solution. 

 (4. ) Wash in water. 

 (5.) Alcohol, oil, balsam. 



The elastic fibres are bluish-black or black, and the surrounding tissue light 

 bine. What Herxheimer described as "spirals" in the lower layer of the 

 epidermis are spiral fibrils proceeding from the lowest layer of the cells of the 

 epidermis, as shown by Kronmayer (p. 327). 



(iii.) Unna's Method. Place sections of the skin for 12-24 hours in the 

 following mixture : 



Orcein . . . .0.5 gram. 



Absolute alcohol . . . 40 cc. 



Water . . . . 20 ,, 



Hydrochloric acid . . .20 drops. 



The sections arc afterwards decolorised in very dilute I1C1 containing some 

 alcohol. A full account of the arrangement of the elastic fibres is given by 

 Lenthoefer. 1 



18. Sweat-Glands of Axilla. Make V.S. of the skin of the axilla hardened 

 in alcohol. Stain in hrematoxylin, or stain in bulk and cut in paraffin. The 

 sweat-glands, and particularly the coils, are very large. In these glands it is 

 easy to see the smooth muscular fibres outside the lining 



epithelium of the secretory part of the coil (fig. 313). 



19. Development of Hairs. Make V.S. of the skin of 

 a foetus at the fourth to the fifth month, after being 

 hardened in Miiller's fluid (12-15 days) an d then in 

 alcohol. Stain a small piece " in bulk " in borax-car- 

 mine, and cut in paraffin. The sections may also be 

 stained subsequently with methyl-green. Mount in 

 balsam. 



20. Double-Staining of Hair-Follicles. (.) Make V. FIG. 313. T.S. Socre- 

 and T. sections, and stain some with eosin and hfemato- tory Part of Sweat- 

 xylin, and others first with picro-carmine (12 hours) and Nuclei of smooth 

 then with methyl-green iodide. The latter preparation muscle. 



is specially beautiful, and both T.S. and L.S. should be 



stained by this method. The scalp is best hardened in potassic bichromate. 



Harden other pieces in alcohol. Methyl -green stains the inner root-sheath 



green. 



(b.) Stain with aniline-blue and safranin. Henle's sheath is rosy, Huxley's 

 blue. 



(c.) Or stain in safranin in a weak alcoholic solution of picric acid. 



21. Tactile Hairs. Harden the skin containing the large tactile hairs of 

 a rabbit or cat in alcohol or Miiller's fluid. Make T.S. and L.S. Outside the 

 sheaths of the hair-follicle, already described, there is a large blood-space 

 traversed by tnibeculse, and thus presenting the characters of cavernous 

 tissue. 



22. Nail (double-stained}. Picro-carmine and methyl-green. 



23. Blood-Pigment in Hair (H). Examine in normal saline one of the 

 large " feelers" from the lip of an albino rabbit (S. Mmjer}. At some part of 

 the hair in its centre a red pigment 'hremoglobm may be seen. 



24. Fibrillation of Protoplasm of Epithelial Cells (Kronmayer}.* By means 

 of Weigert's fibrin-staining method (Lesson III. 20) Kronmayer has demon- 



1 Topographic d. Elastisclicn Geuv.be, Leipzig, 1892. 



- "Die Protoplasmafaserung d. Epithelzelle," Archiv f. mik. Anat., xxxix. 

 p. 141, 1892. 



