452 THE SALIVARY GLANDS, BY E. F. W. PFLUGER. 



columnar cells, without any difference being perceptible be- 

 tween the axis cylinder and the fibrils of these cells, we may 

 legitimately describe the nerve as extending to the point where 

 it joins the substance of the body of the cell. That is the most 

 natural explanation that can be given. This explanation, how- 

 ever, possesses the greatest significance in regard to the mode 

 of development of the glandular epithelium, because it directly 

 follows that the young nuclei originate in the axis cylinders, 

 and that the gland cells which at a later period seem to con- 

 stitute a thickening of the axis cylinder bud forth, as it were, 

 from the nerves. This explanation renders it intelligible why 

 the nucleus of the columnar cells are so indifferent during the 

 multiplication of the epithelium. In opposition to this view, 

 which I regard as the most probable, it may be urged that, in 

 consequence of the intimate fusion of nerve substance and 

 epithelium at the periphery, no sharp limit can be drawn, 

 showing where the one ceases and the other begins ; and that, 

 moreover, it is probable that imperceptibly fine processes are 

 given off by the nucleus of the columnar epithelial cells, which 

 become detached at an early period by fission. That the nuclei 

 of the salivary cells have processes, cannot, however, be re- 

 garded as forming a valid objection to my view, since the young 

 nuclei may really be thickenings of the axis-cylinder fibrils. 



I may further adduce, as a weighty argument in favour of 

 my view, that the fibrils of the axis cylinder do not terminate 

 at the surface of the fully developed salivary cells, but, as in 

 the case of the ganglion cells, may be traced into their very 

 substance. 



Now, since the finest axis cylinders and fibrils extend to the 

 columnar epithelial cells, and are connected with the processes 

 that are in course of development, and since portions of these 

 processes subsequently become large salivary cells, connected 

 with thick medullated nerve fibres, it follows that the nerves 

 must increase coincidently with the young epithelium to which 

 they belong. Amongst these metamorphoses there also occurs 

 a mode of termination of the medullated nerves, to which I 

 some time ago called attention, and which consists in the nerve 

 suddenly undergoing frequent division, then enlarging, and 

 containing finely granular protoplasm, with many nuclei of 



