A CTION OF COL UMNAR EPITHELIUM. 2 T I 



through the vascular wall be due to an eliminative 

 act, it is difficult to see why the passage of other kinds 

 should not be due to elimination. If the escape of 

 the virus of small-pox or scarlatina from the blood be 

 an example of " elimination," surely the migration of 

 an entozoon might be referred to the same process, 

 and we might correctly speak of the " elimination " 

 of a leaf from the branch, or the " elimination " of a 

 hair from the hair follicle. 



In the organism certain kinds of epithelium are 

 concerned in absorption, and certain kinds in secre- 

 tion and elimination. In the first the direction of the 

 flow must be towards the blood, and in the last from 

 the blood. It is obvious that if epithelium ordinarily 

 concerned in absorption is to take part in eliminating 

 matters from the blood, its action must be reversed. 

 The columnar epithelium covering the villi is a 

 remarkable instance of the first form of epithelium, 

 and yet not only has it been inferred that this was 

 concerned in eliminating poison from the blood in 

 cholera, but that there was actually an increased 

 formation of epithelium in this disease, and that the 

 detachment of the epithelium was to be regarded as 

 evidence of a tendency upon its part to separate a 

 poisonous material which had been accumulating in 

 the blood. It was shown, however, in the first part of 

 this section, that epithelium usually eliminates with- 

 out being detached or destroyed, and that we are 

 not justified in inferring that such epithelium could 



