300 MR. H. A. BAYLIS ON THE 



o£ the filaments stained with gold chloride. The cells ap[)eax' to be exactly 

 similar to those in the supra-orbital tentacles, and are equally invisible by 

 other staining methods. 



Before leaving the morphological characters of the epidermis, certain other 

 kinds o£ cells must be mentioned which occur with gi-eat frequency among 

 the ordinary stratified epithelium. Zincone mentions two kinds — namely 



(1) ordinary unicellular mucous glands ("cellule a forma di bottiglia *"), 

 which have their narrow ends on a level with the outer surface of the 

 epithelium. His account of these agrees with my observations. As he sa}S, 

 they are not stained by osmic acid or by chloride of gold, l)ut rem?iin as 

 clear, conspicuous, refractive bodies. They have a small nucleus at the 

 bottom of the cell, surrounded by a thin pvoto[)lasmic residuum. The greater 

 part of the cell is occupied by the mucous secretion. These are ihe only 

 cells, apart from the ordinary epithelial cells, shown in his figure. They are 

 particularly abundant near the base of the tentacles. Some of them are 

 shown in outline in my figure 8, and one from />. oi-ellarls in fig. a, 



(2) If I understand him aright, the only otht-r cells alluded to by him are 

 round or oval cells, more deeply imbedded in the epidermis, iind staining 

 deeply both with osmic acid and c hlorido ol gidd. He says : " Vi sono 

 invece altre cellule di grandezza parimenti notevole, le qu:di hcnchc non 

 presentano la iorma dei cosi detti KoUwn desci'itti dal Mjix Schultze e Fr. E. 

 Schulze, ed invece si presentano di una forma ovale, pure subiscono una 

 reazione particolare non commune alle cellule a muco, si colorano cioe 

 fortemente al cloruro d'oro ed alT aciilo i[)erosmico." As he suggests, they 

 are probably merely an early stage of the mucous cells, and would later 

 migrate to the surface and acquire the characteristic flask-like shape, with 

 an opening on the exterior. As in their final form, they have an eccentric, 

 nucleus surrounded by a little residual protoplasm, and the rest of the 

 globular cell is swollen out with the secreted matter, Mhich becomes deep 

 black when ti-eated with osmic acid. With ordinary methods of staining, 

 such as borax-carmine, these cells remain clear. A typical example of such 

 a cell is shown in fig. 9 (M). See also figs. 2 and 4 {M). Two such cells, 

 treated with osmic acid and isolated, are also shown in fig. 10. 



In addition to these two forms of mucous cells, 'it seems to me that there 

 are also present still more conspicuous cells, which may fairly be compared 

 with the " Kolben " described and figured, especially for Fetromyzov, by 

 F. E. Schulze [4]. These are very large elongated cells, extending, as a 

 rule, through the whole thickness of the epidermis. In sections they always 

 appear to lie in a space hollowed out \\\ tlie ordinary stratified epithelium; 

 an appearance which may, perhaps, be due to shrinkage. As Schulze says, 

 there is no apparent membrane surrounding these cells, and they appear to 

 be of a semi-fluid consistency (" dickfliissige Consistenz ") ; but after harden- 

 ing, they can easily be isolated by teasing or pressure, and then appear as 



