50 OF VITAL MOTION. 



coloured cells of the epidermis. On the other hand, 

 the history of plethora, when contrasted with the 

 opposite effects of anasmia, may serve to show that free 

 nutrition is associated with an abundant development 

 of organic force. 



It would appear, also, that there are phenomena in 

 animal bodies which seem analogous to " rotation" (of 

 the vaguer sort,) and that these are referrible, in part 

 at least, to physical agencies. Dr. Addison, indeed, 

 pointed out some time ago the existence of moving 

 molecules in many forms of free cells, as in those of 

 mucus, pus, and lymph, and also in the colourless 

 cells of the blood ; and I have heard him state, that 

 after watching these movements until they had ceased, 

 he has repeatedly seen them renewed and made as 

 brisk as ever by accidentally placing the watch-glass 

 in which the fluid had been contained upon the warm 

 mantelpiece. It would thus appear that the process 

 of cooling after removal from the body had arrested 

 their movement, and that they were renewable by 

 warmth, and in this manner we may detect further 

 proofs of the continued operation of these agents. 



It appears, also, that the movements of " vibratile 

 cilia" continue so long as the supporting cells retain 

 their integrity and are acted upon by warmth, and 

 that they cease in opposite conditions ; and this being 

 the case we may obtain some light as to the cause of 

 these singular phenomena. To find any proof of ex- 



