THE THIRD HUXLEY LECTURE 531 



Inflammatory congestion also may be brought about bv nervous agencv. 

 This fact being of fundamental importance, and not perhaps universally recog- 

 nised by pathologists, I may describe briefly two unpublished experiments with 

 regard to it which I did shortly after the time of which I have been speaking. 

 Inflammatory phenomena being of a very languid character in the frog, I had 

 resort to a liigher animal. One of the experiments was simply passing a silk 

 thread through a fold of skin in a rabbit's back and knotting the ends together. 

 When forty-eight hours had elapsed, the animal having been killed, I removed 

 the portion of skin concerned and examined its under surface. The thread 

 was covered with a yellow line of lymph, around which there was intense scarlet 

 redness for about a quarter of an inch in every direction, contrasting stronglv 

 with the paleness of the healthy structures around. And on microscopic 

 examination I found that this depended (to quote from my notes of the time) 

 'partly upon ecchymoses, but chiefly upon well-marked inflammatory congestion 

 of the minutest vessels of the subcutaneous tissue and the deeper parts of the 

 skin '. 



The other experiment was performed twenty minutes before the first, upon 

 a part of the same animal which, being more sensitive, was more likely to show 

 the effects of nervous disturbance. By means of a fine sewing-needle I passed 

 a delicate thread of silk through the superficial layers of the left cornea, and cut 

 the ends of^ close with scissors. Next day the eye was much inflamed and its 

 condition was aggravated on the day following, while the other eye remained 

 healthy. As I have already said, the rabbit was killed on the expiry of forty- 

 eight hours. This having been done by pithing, I at once divided the blood- 

 vessels in the neck while the heart was still beating, so as to allow all blood that 

 was free to flow to escape from the head. I then removed the two eyes and 

 cut them both across transversely midway between the cornea and the optic 

 nerve, and compared the inflamed eye with the healthy. I will not detain you 

 with a description of the anterior halves of the globes, though they were very 

 interesting, but will at once speak of their posterior portions, more remote from 

 the part where the exciting cause had been in operation on the left side. In 

 that eye the retina was much more readily detached than in the right, and 

 showed small spots of ecchymosis, while the blood-vessels were more conspicuous. 

 The two chloroids presented a striking contrast ; ' the vessel in the right eye ' 

 (to quote my notes again) ' being not at all conspicuous, while in the left eye 

 the membrane was scarlet ; and this depended not merel\- uihhi fullness of 

 red vessels but upon darker tint of their contents in consequence of excess of 

 the corpuscles.' 



It is matter fur discus>iun how inlkunmatory congestion is brought about 



