144 DE, E. KLEIN. 



in thin sections that the fibrils of the outer cell portion are in, 

 connection with the ifitranuclear nettoork, hence the membrane 

 of the nucleus presents the appearance of a perforated membrane. 

 Pfliigeri and Lavdowsky^ assert that when a part of this "rod- 

 epithelium'^ is viewed from the surface we see a uniformly dotted 

 substance ; and Heidenhain^ has also maintained^ with reference 

 to the epithelium of the convoluted tubes of the kidney, on the 

 occasion when he first described those cells as being in the 

 principal part composed of rods or fibrils, that in the surface 

 view these cells appear uniformly dotted, owing to the rods being 

 seen endwise. Lavdowsky^ confirms this for the embryonal 

 kidney. "Without, of course, doubting for a single moment 

 that what Heidenhain and also Lavdowsky isolated in the respec- 

 tive kidneys were rods or fibrils, I must differ from both and 

 Pfliiger, not only with regard to the cells of the submaxillary 

 gland, but also with regard to those of the convoluted tubes of 

 the kidney, for a careful inspection of the surface of the rod- 

 part of the epithelium in both cases shows, not merely a 

 dotted appearance, bid a network, i.e. dots with short anastomos- 

 ing branches, the dots being of course due to rods seen end- 

 wise. So that the rod-part of the epithelium does not merely 

 contain a bundle of rods or fibrils, as maintained by Pfliiger, 

 Heidenhain, Lavdowsky and others but a reticular substance 

 which possesses a pre-eminently longitudinal arrangement. 

 Whether the rods or fibrils are in many instances membranous 

 expansions or not, I am not able to say, although looking at 

 them endwise I seem to notice in some places appearances more 

 compatible with the presence of the latter than the former. The 

 same arrangement is possesssed by the " rods" in the medullary 

 sheath of nerve fibres, described by Lantermann and MacCarthy, 

 that is to say, the medullary sheath is not merely composed of 

 vertical rods, but of a reticular substance. I shall have occasion 

 to refer to this appearance more in detail in the third part of 

 this paper. 



In both cases of glands hitherto described there are found a 

 number of alveoli, lohich possess no " mucous cells, ^' or only traces 

 of them, but which are entirely, or to the greater extent, made 

 up of " granular " or " protoplasmic " cells, with circular cen- 

 tral nuclei. I find either small groups or sections of lobules 

 almost entirely made up ef such small protoplasmic cells ; they are 

 for the most part polygonal, possess one central circular nucleus, 

 they lie very closely together, and appear either to belong to more 

 or less convoluted tubes without any lumen in them, or they are 

 arranged, as in the ordinary alveoh, around a very small lumen, 



' Strieker's ' Handbook,' English trans., p. 431. - L. c, p. 314. 



3 ' Archiv f. mikrosk. Anat.,' Bd, x, p. 5. " L. c, p. 333. 



