RETICULAR AND OTHER CONNECTIVE TISSUES 



293 



to represent a less mature type than the collaginous, one in which 

 the primitive relations of endoplasm and exoplasm still persist to 

 a considerable extent. That this is the case is, perhaps, indicated 

 by the fact that in developing mesenchymal tissue one finds 

 fibrils, bearing similar relations to the endoplasm and exoplasm 

 of the connective tissue syncytium, and which like reticulum 

 blacken with the silver impregnation (fig. 4). 



Cv— --- 



/ 



b-:ps 



,31 



10 



Fig. 10 Accurately drawn from a section of the spleen of man, showing the 

 actual course of fibrils of blackened reticulum through the cytoplasm of fixed 

 connective tissue cells. The parts a of the fibrils end by making a sharp turn 

 which passes out of the plane of the section. The loops formed at b are shaded 

 light, and in the section they lie below the level of the cytoplasm as readily demon- 

 strated by change of focus. The black portions, a, are above the level of the cyto- 

 plasm. Bielschowsky stain. Camera lucida; occ. 1, obj. x^2' hom. im. 



Fig. 11 Areas similar to those shown in fig. 10, but drawn from a section of a 

 lymphatic gland of man. Similar appearances were very numerous in this section. 

 a and 6, as in the preceding figure; cy, cytoplasm;/ cut ends of fibrils; L, lympho- 

 cytes; Nu, nucleus of a fixed connective tissue cell; at the top of the figure a 

 fibril forms a U-shaped loop which passes through the cytoplasm of a "fixed" cell, 

 entering from below and coming out above. Two similar fibers are also shown. 

 Bielschowsky stain, after stained with acid fuchsin. Camera lucida; occ. 1, obj. 

 1^-2 hom. im. 



Yet bearing in mind that we are dealing with a method of 

 impregnation only, and are subject to all the limitations of such 

 methods, one is not fully warranted in drawing inferences of chem- 

 ical similarity between the mesenchymal and the reticular fibrils. 



