EARLY STAGES OF INFLAMMATION. 147 
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 corpuscles, together with a certain, though 
slight degree of adhesiveness, which retains them pretty 
firmly attached together when in the position most favor- 
able 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 ad- 
hesiveness, in consequence of changes in physical circum- 
stances, 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 delieate nucleated membrane which con- 
stitutes 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 charac- 
terised 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 ef- 
fused as a whole among the tissues in the state of health ; 
and this is thought to imply that there subsists a mutual re- 
pulsion between the materials of the capillary wall and the 
elements of the liquor sanguinis, preventing the passage of 
the latter into the pores of the former, except in so far as 
they are attracted by the tissues for the purposes of nutri- 
tion. 
The heart is believed by the author to be the sole cause of 
