EPITHELIUM. 29 1 



CHAPTER XXVII. 

 TEGUMENTARY ORGANS. 



613. Epithelium. One of the chief methods of obtaining 

 preparations giving instructive surface-views of epithelia is 

 the nitrate of silver method. For this, see ante 198, et seq. 

 in the chapter on Impregnation Methods. The reader may 

 also consult with advantage the admirable instructions, given 

 by BANVIER in his Traite technique, p. 246 et seq., and the 

 memoir of TOURNEUX and HERMANN in the Journ. de I'Anat., 

 1876, p. 200. 



Sections are easily made by the usual methods. The best 

 hardening agent for skin appears to be Miiller's solution. 

 This was the conclusion of F. E. SCHULTZE in 1867 (Arch. f. 

 inik. Anat., p. 145), and it is that of TIZZONI, the author of 

 important recent researches on this organ {Bull, delle $c. 

 med. di Bologna, 1884, p. 259). 



For glandular epithelium, it is frequently better to employ 

 a chromic acid liquid, or osmic acid (see, for example, BANVIER, 

 loc. cit., p. 258 et seq.), or absolute alcohol (BLAUE, Arch. f. 

 Anat. u. Phys., 1884, p. 231); " Kleinenberg " is not so good. 



Prickle-cells and inter- cellular canals. Besides maceration, 

 which is one of the most important of the methods for the study 

 of these objects, impregnation may be useful. MITROPHANOW 

 (Zeit. f. wiss. Zool., 1884, p. 302, and Arch. f. Anat. u. Phys., 

 1884, p. 191) recommends the following process : Wash with 

 distilled water the tail of an Axolotl larva ; put it for an hour 

 into 0'25 per cent, solution of gold chloride with one drop of 

 hydrochloric acid to a watch-glassful of the solution ; wash ; 

 and reduce in a mixture of one part of formic acid with six 

 parts of water. 



Macerating Media. For soft epithelia, mild macerating 

 agents, such as iodised serum, one third alcohol, saliva, or 

 Schultze's mixture of saliva and solution of Miiller, or a 



