chap, iv.) THE ORBIT AND EYE. 67 



whooping cough. Blood also may find its way beneath 

 the membrane in fractures of the base of the skull. 

 Haemorrhages beneath the membrane are unlike other 

 extravasations (bruises), in that they retain their 

 scarlet colour. This is due to the fact that the 

 thinness of the conjunctiva allows oxygen to reach the 

 blood and retain for it an arterial character. Severe 

 inflammation of the conjunctiva may lead to con- 

 siderable cicatricial changes, as is the case in other 

 mucous membranes, and especially, perhaps, in the 

 urethra. The contraction of the conjunctiva after 

 destructive processes is apt to lead to entropion. If 

 both the ocular and the corresponding part of the 

 palpebral conjunctiva have been destroyed, the two 

 raw surfaces left will readily adhere ; the lid will 

 become fused to the globe, and the condition called 

 symblepharon be produced. This condition concerns 

 the lower lid, and is generally brought about by lime 

 or other caustics being accidentally introduced be- 

 tween the under lid and the globe. 



In one common form of inflammation of this 

 membrane a number of little " granulations " appear 

 upon the palpebral conjunctiva. These are not 

 real granulations, since no true ulceration of the 

 part takes place, but they appear to be made up, 

 some of nodules of adenoid tissue, others of en- 

 larged mucous follicles and of hypertrophied papillae, 

 all of which structures are normally found in the 

 aiembrane. The condition is known as " granular 

 lids," and is associated with the formation of much 

 new tissue in the deeper parts of the membrane. 

 From the absorption of this new tissue and of 

 these granulations a contracting cicatrix results, 

 leading to much puckering of the membrane, and 

 often to entropion and inversion of the eyelashes. 

 In purulent ophthalmia the cornea is in great risk of 

 destruction, owing to the strangulation of its vessels, 



