166 DR. E. KLEIN. 



fibrillation of their substance. The nuclei of these cells are 

 smaller than those of the cells of the salivary tubes^ are spherical, 

 and very conspicuously crowded, they stain very readily, and hence 

 this part of the tube, i.e. the neck, is very conspicuous in pre- 

 parations well stained in logwood. In the parotid of the dog 

 and ape the neck of the salivary tubes is a very prominent 

 feature ; in that of the rabbit and guinea-pig I have not been 

 able to make it out with sufficient clearness. 



Past this nec/c and nearer to the alveolus we come to the 

 intercalated or intermediary/ part of the authors ; this is a thin, 

 long tube giving off several similar branches ; they all communi- 

 cate immediately with the alveoh. As regards the structure of 

 these intercalated portions, I find that t//e lumen is lined with a 

 special delicate membrane, commencing as such in the inter- 

 calated part ; in some animals e.(/. parotid of rabbit and guinea- 

 pig, it is a continuation of the inner nucleated membrane lining 

 the lumen of the salivary tube, which we mentioned as occurring 

 in some places. Betiveen this inner membrane of the intercalated 

 part and the membrana propria is a layer of flattened, long, 

 transparent cells, each with an oval nucleus placed parallel with 

 the long axis of the tube. These cells are the direct continuation 

 of the epithelium lining the salivary tube and the neck. 



Such is the structure of the interculated tubes in the parotid 

 of the dog, ape, rabbit, and guinea-pig. In the dog and ape, 

 the inner lining membrane is not everywhere so distinct as in the 

 other two animals. 



Now the transition of the intercalated tube into the much 

 larger alveoli takes place in this way : the membrana propria of the 

 former passes into the membrana propria of the latter, the flattened 

 transparent epithelial cells of the former pass directly into the 

 columnar or pyramidal less transparent secretory cells of the 

 latter, while the inner lining membrane above mentioned is 

 continued a short distance into the lumen of the alveoli, in some 

 places still including a nucleus. It is, then, not correct to say 

 (Boll, Ebner, Heidenhain) that the whole intercalated tube 

 becomes surrounded by the secretory cells of the alveoli, since 

 this is the case only with the inner lining membrane. The 

 continuation of this membrane into the lumen of the alveoli is 

 comparable to the centro-acinous cells of Langerhans in the 

 pancreas, in which exactly the same relation as regards the 

 intercalated tube and the alveoli obtains as in the parotid. 



(2) In the submaxillary glands the condition of things varies 

 greatly in the diflerent animals. I must decidedly oppose the 

 statement as to a uniformity existing between the intercalated 

 tubes in the dog and rabbit, as first mentioned by Ebner and 

 endorsed by Heidenhain. In the submaxillary of the dog I find 



