398 Dr. Waller on the Origin of Mucus and Pus-globules. 



these bodies in pus, mucus and in the blood, I may mention 

 that I have before me drawings of mucus and purulent glo- 

 bules, and of the corpuscles obtained from man and from some 

 of the cold-blooded animals. All these drawings have been 

 carefully executed under the camera lucida, at different times; 

 and they resemble each other so closely as to render it impos~ 

 sible to give any distinctive character to recognise one from 

 the other. 



In consequence of this striking resemblance, observers have 

 already supposed that the corpuscles of the blood give rise to 

 those found in mucus and pus, and that these are simply cor- 

 puscles extravasated or filtered from the blood. An important 

 observation has moreover corroborated this theory, namely 

 that of the accumulation of the corpuscles at the inner sides 

 of vessels which are subjected to any prolonged irritation. 

 This theory has principally been known in this country from 

 the talented observations of Mr. W. Addison. 



On the other hand, it has appeared to other physiologists 

 so improbable to suppose the perforation of the capillary ves- 

 sels by the corpuscles, that they have come to the conclusion 

 that they are not derived from the blood, but, like semen or 

 milk, are formed on the secreting surface, in virtue of some 

 plastic power of the fluids which are effused upon it. This 

 opinion is maintained, with some modifications of trifling im- 

 port, by Muller, Autenreith, Donne, &c. 



My observations respecting the almost exclusive accumu- 

 lation of the corpuscles in the vessels of the frog's tongue 

 which are most exposed to irritation, was already an advance 

 in the inductive proof of the first theory; but it is especially 

 the observations at the end of the preceding paper which give 

 the crowning evidence in its favour. I have already had the 

 satisfaction to find that they have been confirmed by other 

 observers to whom I have shown them. On my own part, I 

 have repeated them in very numerous instances with invariable 

 success. 



Let us now examine the admirable manner in which nature 

 has solved this apparent paradox, of eliminating, from a fluid 

 circulating in closed tubes, certain particles floating in it, with- 

 out causing any rupture or perforation in the tubes, or allow- 

 ing the escape of the red particles, which are frequently the 

 smaller of the two, or that of the fluid part of the blood itself. 

 In order to allow less latitude to the imagination, I will in the 

 first place describe faithfully, from a number of others, one or 

 two complete observations, as I have noted them down at the 

 time of experimenting. 



Obs. 1. — A frog's tongue was secured in the usual manner. 



