Franklin V. Mall 36 L 



The examination of nunicrous thin sections cut in parattin and 

 stained by Weigert's method showed that the amount of elastic tissue 

 in the follicle is by no means constant. Occasionally no fibrils at all 

 could be demonstrated by this method while frequently they were only 

 at the periphery of the follicle. Care must be taken in such tests not 

 to stain the sections too long, for the reticulum, and the wdiite fibrous 

 tissue of the capsule, take up considerable stain and thus lead to confu- 

 sion. The only definite tests are those in which the surrounding elastic 

 tissue stains intensely, leaving the white fibrous tissue colorless. In a 

 beautiful specimen of a Peyer's patch the elastic tissue accompanies 

 every reticulum fibril into the follicle for two-thirds of the distance to 

 its center and then ends quite abruptly. When not highly magnified 

 it appears as if the reticulum itself were stained intensely, but with 

 the 2 mm. oil immersion it is very apparent that each fibril of reticulum 

 is encircled with several delicate elastic fibrils. At the center of the 

 follicles there are no elastic fibrils at all. . The variation in the amount 

 of elastic tissue in the lymph node suggests at once whether it is not 

 due to some pathological process, for most of my sections were from 

 human lymph nodes which had been cut for other purposes. The 

 recent work of Melnikow-Easnednekow,'' Flexner,'' and others upon the 

 formation of elastic tissue in cirrhosis of the liver suggests this view. 

 The observations are sufficient, however, to show that elastic fibrils 

 accompany some, but not all. of the reticulum fibrils in the follicle of 

 the lymph node. Furthermore, the development of reticulum precedes 

 that of elastic tissue. 



Sl'in.— It is extremely difficult to obtain clear pictures of the devel- 

 opment of elastic tissue of the skin, when the youngest fibers which 

 take Weigert's stain are studied in relation to the nuclei or to the 

 white fibers. Practically no better results are obtained from the 

 embryo than from the adult. In each case there are sharply defined 

 fibers"^ and that is all. On the other hand, when the skin is macerated 

 by boding frozen sections in 1 per cent acetic acid until the white fibers 

 are mostly dissolved or are converted into a jelly-like mass the relations 

 are somewhat distorted but the results are instructive, when compared 

 with sections of the skin and of the larger arteries which have been 

 stained by Weigert's method. 



The elastic tissue of the arteries of the skin stains by Weigert's 

 method in embryos from 20-25 cm. long. There are no elastic fibers 

 within the skin itself. The clear areas at the roots of the hairs are 



i-iMelnikow-Rasnednekow, Ziegler's Beitrage, 26, 1899. 

 '5Flexner, Univ. Med. Mag., 1900. 



