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study of the early stages of inflammation in the foot of the frog will 

 apply in all strictness to the same morbid process in man." 



The remainder of the introduction is occupied with a sketch of the 

 principal theories which have been proposed to account for the 

 obstruction to the progress of the blood- corpuscles in the early stages 

 of inflammation. 



The first section of the paper is devoted to the discussion of the 

 aggregation of the corpuscles of the blood. It is shown by the author 

 that the rouleaux "are simply the result of the disk-form of the cor- 

 puscles, together with a certain, though slight degree of adhesiveness 

 which retains them pretty firmly attached together when in the posi- 

 tion most favourable for its operation, namely when flat surface is 

 applied to flat surface, but otherwise allows them to slip very readily 

 upon one another." The aggregating tendency of the red disks is 

 thus regarded as a phenomenon similar in kind, though inferior in 

 degree, to the well-known adhesiveness of the white corpuscles. It 

 is further shown, from numerous experiments, that the red corpuscles 

 vary remarkably in adhesiveness, in consequence of changes in phy- 

 sical circumstances, or very slight chemical action. 



Section II. is on the structure and functions of the blood-vessels. 



Allusion is made to a paper by the author which will shortly appear 

 in the Transactions of the Royal Society of Edinburgh, where he has 

 recorded the observation, that in the smallest arteries of the web of 

 the frog's foot the middle coat is composed of muscular fibre-cells 

 wrapped spirally round the internal membrane. The parietes of the 

 minute arteries are thus provided with a most efficient mechanism 

 for diminution of calibre, and contrast in this respect very strikingly 

 with the delicate nucleated membrane which constitutes the wall of 

 a capillary. The functions of the two sets of vessels are described 

 as being in harmony with these differences in structure ; the arteries 

 being specially characterized by contractility, while the capillaries 

 exhibit only such changes of calibre as are explained by elasticity. 



The thinness of the capillary wall is believed to favour the mutual 

 interchanges between the blood and the tissues, but the consideration 

 of some facts of physiology leads the author to the conclusion, that 

 notwithstanding the distending force of the current of blood, the 

 liquor sanguinis is not effused as a whole among the tissues in the 

 state of health ; and this is thought to imply that there subsists a 



