GLANDULAR EPITHELIUM AND DIVISION OF NUCLEI. 413 



decessors^ and I can therefore omit detailed references to 

 other observers. 



We notice in such a section that the nuclei of the two 

 deeper layers of cells are oval, and placed vertically to 

 the surface ; they possess a sharp limiting membrane, and 

 contain a uniform reticulum, intranuclear network, varyinjj 

 between the reticulum of minute fibrils to that of a spongy 

 honeycombed structure. The interstitial substance of this 

 reticulum is homogeneous and transparent in logwood. There 

 is no trace of any nucleolus. Division of nuclei being 

 limited to these tvvo layers, we are justified in considering 

 them as in a ripe state, and we have, therefore, here much 

 additional evidence that the nucleolus is not a necessary 

 feature in the structure of a nucleus, and that it is alto- 

 gether absent in nuclei, that may be regarded as ripe and 

 fully formed (see figs. 8 and 9, Plate XVIIl). The 

 nuclei of the middle strata of the epidermis show a more 

 or less distinct reticulum, and in it larger or smaller accu- 

 mulations — nucleoli ; the interstitial substance is homo- 

 geneous, but in many cases more or less stained in hsema- 

 toxylin. 



In all cases, however, we find the small, bright dots 

 included in the network ; these, as stated by me on so many 

 occasions, are fibrils of the reticulum viewed in optical 

 section. 



Amongst the nuclei of the two deep layers of cells we 

 notice some that are somewhat larger than the rest, and 

 contain very beautiful, deeply stained fibrils, either twisted 

 and coiled into a more or less dense convolution (Flemming), 

 or arranged like a basket (Eberth), viz. most fibrils are peri- 

 pheral, and have a transverse direction ; hence, the surface 

 of the nucleus in the latter case shows a transverse striation. 

 But in both instances, viz. the^convolution" and the'' basket," 

 the fibrils are connected into a network (see figs. 10 — IS, Fl. 

 XVIII) . The membrane of the nuclei showing this arrange- 

 ment is less marked than in the other nuclei of the ordi- 

 nary kind, appearing not as a continuous structure, but 

 more or less due to the close position of the fibrils. 



These forms are regarded by Flemming as the initial stages 

 of the coming division of the nucleus. I do not find anything 

 that would be contrary to such an explanation. Like 

 Flemming, I find all forms intermediary between the ordinary 

 nucleus as above described and the enlarged nuclei with 

 "convolutions" or basket-shaped arrangement of the intra- 

 nuclear network. 



In some cases the " convolutions " are very dense, and 



