56 FIFTH LECTURE. 



eye as quite dissimilar things, and which in reality are very 

 nearly related. 



The usual system of anatomy recognizes primary bundles, 

 that is, simple fibrous cords. A portion of these, held 

 together by loose connective tissue, constitute secondary 

 bundles, and from these latter tertiary are formed. 



We have, firstly, as a badly selected name runs, "form- 

 less " connective tissue. Soft and extensible, it forms the 

 general filling up substance of the organism. Membraniform 

 connective-tissue bundles with homogeneous interstitial sub- 

 stance (Fig. 51), form thin lamellae, which superimposed on each 

 other at various angles, incompletely limit cavities. These 

 are the so-called " cells" of the older anatomists, who gave 

 our tissue the name of cellular tissue. The lamellae are often 

 nearly in contact with each other, but the space enclosed by 

 them may also be completely filled by collections of fat cells. 

 Where structureless connective tissue occurs in greater quan- 

 tity it has received special names. Thus, one speaks of sub- 

 cutaneous, submucous and subserous connective tissue. 

 Elastic elements are here met with, sometimes scanty, some- 

 times more profuse, but never in excess. 



We now come to the formed connective tissue, with its nu- 

 merous varieties. This constantly arises from the formless 

 variety without any sharp demarcation, so that this division 

 of the anatomists is entirely artificial. 



We enumerate here : 1. The corneal tissue. The cornea 

 has on its anterior surface stratified pavement epithelium, on 

 its posterior a simple cell covering. Under both epithelial 

 coverings there is a hyaline layer. The anterior is called the 

 lamina elastica anterior, the posterior the Descemet's or De- 

 mours' membrane. The hyaline corneal tissue consists of a 

 net-work of decussating bundles, which may be divided into 

 fibrillae of extreme delicacy. The whole is permeated by a 

 system of passages which have a sort of parietal layer. In 

 these lie the " corneal capsules," which are flattened cells, 

 comparable to a paddle-wheel. Wandering lymphoid cells 

 are also not wanting. 



