OBSERVATIONS ON STRUCTURE OF CELLS AND NUCLEI. 165 



which organ I made specimens either in chloride of gold, or 

 spirit, or in chromic acid, I miss a nucleolus in the majority of 

 epithelial cells. These contain a uniform network of fibrils. And 

 I will take this opportunity of saying that the statements by 

 MayzeP and Eberth,- to the effect that during the regeneration 

 of epithelium those nuclei that contain filaments, or a network of 

 them, are peculiar forms of developing nuclei, is in so far 

 erroneous, as every nucleus contains such a network. But it is 

 quite possible that under those special conditions the intra- 

 nuclear network becomes more prominent and distinct, and 

 therefore more easily visible, although I do not notice in my 

 specimens any marked difference in this respect. 



The cells of the middle layers of the epithelium of the human 

 CESophagus, obtained soon after death, show the intracellular net- 

 work and fibrils passing from one cell to the other. If a section 

 through this epithelium be examined with the new excellent -y-'.^ 

 inch oil-immersion of Zeiss, the intranuclear network, the con- 

 nection of this with the intracellular one, and the passage of 

 bundles of fibrils from one cell to the other, is as distinct as one 

 can wish. 



In the flattened cells of the superficial layers of the epithelium 

 of the first passages of the alimentary canal, I cannot trace the 

 intracellular network with distinctness, but the nucleus, except 

 in the most superficial cells, still contains the network. The 

 nuclei of even the most superficial cells of the epithelium of 

 cornea of frog, newt, or mammalian animal, when examined fresh 

 or in sections after hardening in chloride of gold and then spirit, 

 or spirit alone, or chromic acid, show the intranuclear network 

 with more or less distinctness. 



I have seen the intranuclear network in several instances even in the 

 squamous cells spontaneously detached from the epithelium of mouth and 

 floating in saliva. 



The same structure, i.e. intracellular and intranuclear network, 

 is also possessed by the epithelial cells of the deeper and middle 

 stratum of the rete Malpighii of epidermis. The "prickles" 

 between these cells, first observed by Max Schultze ^ in the cells 

 of the middle layer of the epidermis and laminated epithelium of 

 oral cavity, are directly connected with the intracellular network, 

 and form at the same time the connecting fibrils between adjacent 

 cells (see fig. 19). This is quite in conformity with the observa- 

 tions of Bizzozero* and Heitzmann^ This last-named author 



> ' Centralblatt; No. 50, 1875. 

 - 'Virchow's Archiv,' Band 67. 

 3 'Centralblatt,' 1869. 



* ' Studi f. n. Laboratorio patol. d. Univ. d. Pavia,' 1870. 



* ' Unters. liber d. Protoplasma, ' Sitzungsber. d. Akad. d. Wiss./Band, 

 l^vii, 1873 J ii, p. 14 of ' Separatabdruck,' 



