468 THE LACHRYMAL GLANDS, BY FRANZ BOLL. 



the alveolus. If the fluid be moved by pressure on the 

 covering glass, the transition of such a crescentic cell into a 

 stellate multipolar cell may often be observed under the 

 microscope. In young animals a small quantity of granular 

 substance occupies the centre of the cell, surrounding the 

 .usually round nucleus, which contains no distinct nucleolus. 

 In older animals this small remains of protoplasm has almost 

 entirely disappeared. The substance of the flat, frequently 

 quite ribbon-like processes is pale, and sometimes finely longitu- 

 dinally striated. They divide dichotomously at more or less 

 acute angles, and not unfrequently a thick process may be 

 seen suddenly breaking up into several branches. 



Some of the processes of these stellate cells penetrate, as 

 may also be shown in isolation preparations, between the epi- 

 thelial cells of the alveolus themselves. It was maintained by 

 Pfliiger, who first accurately examined them in the salivary 

 glands, that these processes are directly continuous with the 

 processes of the secretory epithelial cells, and that from this 

 connection with true epithelial structures the nervous nature 

 of the stellate cells can be demonstrated. Although I am in 

 possession of numerous specimens in which at first sight there 

 appears to be a direct continuity bet ween the two cells,! have not 

 been able to satisfy myself that such a connection really exists. 



3. THE INTERSTICES OF THE ALVEOLI. Whilst the inner sur- 

 face of the membrana propria is lined by the epithelial cells of 

 the alveolus, the external surface remains free, and during life 

 forms the boundary of a space filled with lymph, which, in the 

 case of each parenchymatous body of the gland, occupies the in- 

 terval between the external wall of the capillaries and that of 

 the alveoli, and the presence of which can be rendered evident by 

 the most diverse methods, as by simple puncture injections, or 

 by the production of artificial oedema in the gland, in Ludwig's 

 method. 



The form and extent of these spaces in the secretory paren- 

 chyma must obviously be extremely complicated. In sections 

 of the several parenchymatous bodies, when injected, which is 

 best accomplished with cold fluid Berlin blue, each alveolus of 

 the gland, without exception, appears to be surrounded by a. 



