450 CONJUNCTIVA AND SCLEROTIC. 



and beneath the membrana nictitans, and are pre-eminently de- 

 veloped in the upper lid. He regarded them as pathological 

 structures on account of their irregularity and inconstancy, 

 on account of the roughness that results from their presence, 

 and on account of the morbid phenomena they occasion, as, 

 for example, the injection which extends to the vessels of the 

 bulb itself. Henle designates them " trachoma glands." W. 

 Krause also found lymph follicles in the Rabbit and Fox, and in 

 Birds. He first maintained that their presence was general, 

 and considered them to be physiological structures. 



Kleinschmidt found the same kind of follicles in Man and 

 in domestic animals. 



Huguenin (under Frey's direction) gave a similar descrip- 

 tion. He found the vessels of the connective tissue narrower, 

 and the trabeculse thinner, near the periphery of the follicles, 

 whilst at the centre the meshes are larger, and the trabeculse 

 thinner. The tissues lying between the follicles are traversed 

 by lymph cells. In this tissue lymph paths occur in the form 

 of elongated oval spaces without trace of vascular walls. 

 Blood vascular injections exhibited a rich system of branches 

 in the interfollicular substance. The follicles are surrounded 

 by arterial vessels, but their caps are poorly supplied. 



Blumberg (under Stieda's direction) stated that in the Pig 

 the mucous membrane of the conjunctiva, with the exception 

 of the tarsal portion, is composed of adenoid tissue, and pos- 

 sesses trachoma follicles; these last however are absent in young 

 Pigs. In the Dog the matrix of the mucous membrane, as 

 well as that of the conjunctival ccecal sac, is composed of 

 adenoid tissue; in the tarsal conjunctiva, the reticular tissue 

 contains only a sparing amount of lymph cells. Numerous 

 trachoma follicles are present in the mucous membrane of the 

 membrana nictitans, and often also upon its external surface ; 

 on the tarsus, on the other hand, it is only occasionally that 

 trachoma follicles are met with in great numbers ; at the line 

 of reflection, trachoma follicles pass apparently by a process 

 of gradual transition into the adenoid tissue ; in the conjunc- 

 tiva bulbi, trachoma follicles frequently occur. In new-born 

 Dogs neither adenoid tissue nor trachoma follicles are present. 

 Similar relations exist in the Rabbit, Horse, and Ox; in the Cat, 



