PAKENCHYMATOUS KERATITIS. 339 



the result. This is what you observe when a ligature is 

 anywhere drawn through the skin. If on the following 

 day the immediate vicinity of the thread be examined, 

 an active enlargement of the cellular elements is found, 

 quite irrespective of the distribution of vessels and 

 nerves in the part. 



There is, as you see, an essential difference between 

 what I here lay down and the opinions which have gene- 

 rally been advanced with regard to the proximate causes 

 of these swellings. According to the old maxim : ubi 

 stimulus, ibi affluxus, it was generally conceived that 

 the first thing which took place was an increased afflux 

 of blood (which was itself referred by the neuro-patho- 

 logists to the excitation of sensitive nerves), and then 

 that the immediate consequence of the increased afflux 

 was an increased excretion of fluid from the blood, 

 constituting the exudation which filled the part. 



In the first timid attempts which I made to alter this 

 conception, I employed the expression parenchymatous* 

 exudation, retaining the term exudation, out of deference 

 to prevailing opinion. I had, namely, convinced my- 

 self that in many places where a swelling had occurred, 

 there was absolutely nothing else to be seen than tissue. 

 In a tissue which consisted of cells, I could, after the 

 swelling (exudation) had taken place, still see nothing 



* The term Parenchyma was first employed by Erasistratus of Alexandria to de- 

 signate the mass of tissue which lies between, the vessels of apart, and in his opinion 

 formed a kind of affusion from them. Thus Galen says (Isagoge s. Introductio, 

 cap. xi.): u Cerebrum ex nullo principal! vase compositum esse videtur Erasistrato, 

 eoque nutriment! parenchyma, i. e., affusio, ipsi esse videtur." In the same way 

 the word is used by Vesalius (De humani corp. fabrica, lib. V., cap. 7) and by 

 Thorn. Bartholin (Anatome, lib. I., cap. 14), for the proper substance of the liver, 

 lying external to, or between, the vessels. It therefore essentially denotes the 

 tissue of which an organ is constituted. In a narrower sense those constituents of 

 an organ which are peculiar to it, and give it its specific character, may be distin- 

 guished as its proper parenchyma, in contra-distinction to its merely interstitial 

 tissue. In my book the term has been used in both of these senses. From a MS. 

 Note by the Author 



