THE CONNECTIVE SUBSTANCE GROUP. 79 



adult tissue become extremely small, and are represented by 

 the dark markings seen in them. Thin, of London, has claimed 

 that they originate in branching corpuscles, which by their 

 coalescence form the network, and the remains of the nucleus 

 may be shown by hsematoxylin. These markings may, it is 

 true, be seen in the ligamentum nuchse of. the ox, but it is 

 doubtful whether they are nuclei or mere clefts in the tissue. 

 Examination by the author, with such high powers as Gund- 

 lach's No. 15 immersion, and Wale's ^u, have failed to clear 

 up the matter. 



Good examples of human elastic tissue are found in the 

 sloughs of ulcers and in the sputa of phthisical patients. 



In some portions of the body these networks are stouter, 

 as in the bronchi and trachea ; here they almost form a layer 

 by themselves ; some of the fibres are even said to have a 

 sheath. 



There is a variety that has been called, by Henle, perforated 

 membrane . It is found in arteries and veins. The fibres are 

 broad and the meshes very small. There are also "continuous 

 elastic membranes." They are made up of fibrils, react chemi- 

 cally like elastic tissue, and have no meshes. Such is Bow- 

 man's elastic membrane in the human cornea, which is very 

 distinct in man, also Descemet's membrane the posterior 

 elastic membrane of the cornea. 



In various parts of the body, beneath the epithelium, there 

 are other elastic membranes which, will be noticed in their 

 proper places. The elastic membrane, made of endothelium, 

 and forming the basement membrane of gland-ducts, must not 

 be confounded with those first described. 



The growth and development of connective tissue varies ac- 

 cording to the particular type. It is probable, however, that 

 all the corpuscles are first round, but soon become flattened 

 and have a delicate envelope (Fig. 32, &). 



About this is a further lightly attached investment, which, 

 uniting with those of other similar bodies, is the commence- 

 ment of the intercellular substance. At first the plate-like 

 bodies lie in niches, as it were, in the intercellular substances, 

 and if one is brushed out it leaves a socket behind it (Fig. 32, c). 

 They are often arranged in rows, as in the drawing, which was 

 taken from a fibroma of the scalp. As the intercellular sub- 

 stance increases the corpuscles become smaller, while imme- 



