MEMOIRS. 



On the Term Endothelium. By Michael Foster, M.D,, 

 F.R.S., Prelector in Physiology, Trin. Coll., Cam. 



The word " endothelium " has been recently introduced 

 into histology, and the use of it has rapidly become common, 

 if not general. The speedy acceptance of a new term may, 

 in many cases, but not in all, be taken as an indication that 

 something of the kind was wanted ; and the already frequent 

 use of " endothelium," both by Continental and English 

 histologists, would seem to show the need of some other 

 phrase besides '' epithelium." Nevertheless, there are cogent 

 reasons why the new term should not be allowed to take any 

 further root. 



In the first place, its etymology is of the most grotesque 

 kind. This is of course an objection of secondary value ; 

 but still it carries some weight. When a term has come into 

 daily use, witli a clear, well-defined meaning attached to it, 

 it does not matter much what its etymology is or how it is 

 spelt, except on historical grounds. Many terms get so 

 altered in their meanings before they finally acquire a per- 

 manent application, that the chief interest in their etymology 

 is confined to the light it throws on the ideas of the man who 

 first introduced them. This is the chief reason why new 

 terms should be etymologically correct, in order that future 

 inquirers may read back through them into the minds of 

 earlier observers. When a word is etymologically pure non- 

 sense, this is apt to become impossible. Such is the case 

 with endothelium. 



It appears to have been first introduced by His, to desig- 

 nate the kind of epithelium (pseudo-epithelium, undchte epi- 

 thelieti ") which is found lining the vascular, lymphatic, and 

 serous cavities of the body, in contradistinction to the renl 

 epithelium of mucous membranes. He says (Die Haute und 

 Hohlen des K'drpers. Academisches Programm. Basel, 1865, 

 p. 18) :~ 



VOL. XIV. NEW SEK. P 



