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regular masses. These masses when liberated form highly refractive 

 globules. Frequently, after the liquefaction is quite well advanced, the 

 membrane is filled with a row of these highly refractive globules. 

 The empty membrane is not highly refractive and seems to be homo- 

 geneous. 



When reticulum is treated in the foregoing manner it is in no 

 way affected. It reacts throughout as the membranes of elastic tissue 

 fibrils. — When reticulum is thus digested it must be spread out 

 before the individual fibrils can be seen, otherwise the fibrils clump 

 together and appear as a mass of granules. 



We have, therefore, of homogeneous connective tissue fibrils two 

 distinct sets: 



1) white fibrous. 



2) yellow elastic. 



The elastic fibril is composed of a gelatinous interior, viz. elastin, 

 and a membrane, the membrane being identical with the 

 reticulum fibril. 



It is of interest to know how the elastic tissue is connected with 

 the reticulum. This may be well studied in the spleen and in the 

 lymphatic glands. The capsule of the spleen is composed in large part 

 of minute elastic fibrils which are extended, in bundles, into the spleen 

 substance. These in turn anastomose directly with the reticulum fibrils 

 of the spleen pulp. 



It is, therefore, seen that the elastic tissue can be broken up into 

 two pacts; a homogeneous membrane and a tenacious, highly refractive 

 substance. As the fibrils become thinner and thinner, the elastin 

 gradually disappears and nothing but the membranes remain; these 

 form the reticulum fibrils. 



The reticulum is distributed in large quantities throughout the 

 whole body. In the lung it with many elastic fibrils forms the frame- 

 work. In the spleen and lymphatic glands reticulum forms the frame- 

 work nearly altogether. This beautiful framework can be demonstrated 

 nicely by macerating a spleen in water for days and then cutting off 

 the two ends and washing out the pulp. When the pulp is washed out 

 the spleen may be blown up and dried forming a preparation much 

 like an inflated lung. The framework of the mucosa of the small 

 intestine is composed wholly of reticulum fibrils. At points the fibrils 

 arrange themselves into bundles and thus apparently form elastic 

 tissue fibrils. So also in other mucous membranes, — as that of 

 broncheoles, stomach and rectum — reticulum forms, to a great extent, 

 the framework. In the smaller arteries reticulum fibrils form a firm 



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