CHAPTER XXVU. 



TEGUMENTAEY OEGANS. 



654. Epithelium. — Both for surface views and for sections 

 good results are obtained by tlie nitrate of silver method^ the 

 methylen blue method, the percldoride of iron and pyrogallvl 

 method of the Hoggans, § 375, the osniic acid and fyrogallul 

 process, § 374, and by iron-h seniatoxylin. 



For the purpose of separating the epidermis from the 

 corium, Loewy {Arch. milt. Anat., xxxvii, 1891, p. 159) 

 recommends macerating for twenty-four to forty-eight hours, 

 at a temperature of about 40° C, in 6 per cent, pyroligneous 

 acid. Acetic acid of ^ per cent. (Philippson) is also good. 

 MiNOT [Amer. Nat., xx, 1886, p. 575) macerates embryos for 

 several days in 0"6 per cent, salt solution, Miteophanow {Zeit. 

 wiss. Mih., V, 1888, p. 573) for a quarter of an hour in 3 per 

 cent, nitric acid, then 1 hour in one-third alcohol, and, if 

 need be, 24 in stronger alcohol. 



Mayee [Lotos, 2, xii, 1892) exposes the cornea or membrana 

 nictitans of Rana, Bufo, and Mus for half a ininute to the 

 vapour of acetic acid, and then puts it into 0'5 per cent, salt 

 solution. 



For ciliated epithelium see the methods of Engelmann 

 under " Mollusca." 



655. Intercellular Bridges (and Canals), Prickle Cells. — See 

 Ide, in La Gelhile, iv, 1888, p. 409, and v, 1889, p. 321 ; also 

 KoLOSSOW, Arch. mih. Anat., lii, 1898, p. 1. Kolossow used 

 an osmic-acid-tannin stain, § 374. 



See also Fiemminq, Anat. Hefte, 1 Abth, vi, 1895, p. 1. 



Besides maceration, impregnation may be useful ; Miteo- 

 phanow [Arch. Anat. Phys., Phys. Abth., 1884, p. 191) has 

 used gold chloride. 



