164 DR. E. KLEIN. 



met with in the liver of dog, pig and guinea-pig, hardened in 

 spirit and also in chromic acid ; it is this :— The substance of 

 some liver cells presented two more or less distinct zones, one 

 smaller one apparently homogeneous, or faintly granular and 

 stained in heematoxylin ; and a larger one, more transparent, not 

 stained, and showing the above network more or less distinctly. 

 The nucleus of these liver cells is situated peripherally, 

 generally more or less closely to the homogeneous zone, 

 or even in it. The appearances in this latter instance 

 are to a great extent similar to those presented by the cells 

 lining the "gland tubes of the pancreas (Langerhans^ and Hei- 

 denhain." 



7 . The Cells of Laminated Epithelium. 



In this paragraph I wish to notice merely the structure of the 

 more or less polyhedral cells forming the middle and deeper 

 strata of the laminated epithelium, e.g. oral cavity, pharynx, 

 oesophagus and anterior surface of cornea, and of the rete- 

 Malpighii of the epidermis. 



With reference to the epithelial cells of the first, I have con- 

 vinced myself in fresh specimens and in specimens prepared by 

 macerating bits of the above organs in iodized serum, 5 per cent, 

 chromate ammonia — the same method being used as described in 

 my first paper with regard to the examination of stomach of newt 

 — and in sections after hardening with our mixture of chromic 

 acid and spirit, that the substance of these cells, usually described 

 as of more or less uniformly granular appearance, consists of a 

 dense network — intracellular nettvork (see fig. 18 a). The 

 nucleus of these cells is likewise permeated by a delicate network 

 with the usual small bright dots in its nodes (see fig. 18 b). 

 There are occasionally seen in it one or two larger particles, com- 

 parable to the nucleolus auct., but the number of nuclei contain- 

 ing it is in some parts extremely small. I miss them, for 

 instance, in cells in which, of all others, one would have sup • 

 posed they should be present, viz. in the deepest cells of the 

 laminated epithelium, for it is these cells which, according to the 

 observations of most writers, are concerned in the process of re- 

 producing the epithelial cells of the layers above them. Thus, in 

 preparations of the deepest epithelial cells of the cornea I do not 

 find, in the majority of instances, any signs of distinct nucleoli, 

 and the same must be said also of the deepest cells of the epithelium 

 of the oesophagus, pharynx and tongue. Nay^ even in the re- 

 generation of epithelium of cornea after a superficial defect, of 



' 'Beitr. z. mikrosk. Anat. d. Baucbsp.,' Inaus^ural Dissert, Berlin, 

 1869. 

 ' 'Pflilger's Archiv,' Band, x, 559. 



