of Edinburgh, Session 1881-82. 
375 
upon by the same filaments of liquid, the greater the mass 
the slower the progress. 
From these data it is evident that if the coloured blood-corpuscles 
were not of the same, or very nearly the same specific gravity as the 
blood-plasma, the circulation would be a physical impossibility. 
The essence of the blood circulation is, that the majority of the 
corpuscles never touch the walls, and hence undue friction is 
avoided. 
It is further probable that, in hydrmmia or other blood disease, 
where the specific gravity of the plasma is altered, the evidences of 
vascular disturbance may be due to obstruction to the onflow of the 
corpuscles owing to an abnormal relationship between them and the 
plasma. 
The dropsy of albuminuria may be accounted for by the increased 
friction of the circulating blood, caused by the alteration of the 
specific gravity of the plasma, from loss of albumin, giving rise to 
increased tension. This may also account for the passive conges- 
tions and inflammations which occur under these conditions. 
That a proper relationship between the specific gravity of the 
blood-plasma and the bodies suspended in it is absolutely necessary 
for the easy circulation of the blood, is shown by several striking 
observations. Milk, if injected into a vein, has the greatest 
difficulty in passing through the pulmonary capillaries ; its particles 
are too light, and become arrested. Oil globules, when they gain 
entrance into the circulation, as after fracture of certain bones, and 
in the lipsemia of diabetes mellitus, frequently produce fatal results, 
for the same reason. The entrance of air into the circulation brings 
about a fatal result, probably from the same cause. It gives rise 
to air embolism. 
Experiments were next shown with a curved tube to illustrate 
how it is that, as the blood-current becomes retarded in inflammation, 
and as stasis is approached, the leucocytes tend to accumulate at 
the periphery of the vessel. A light sphere, introduced into the 
curved tube with a slow stream cannot pass the first curve of the 
tube, and becomes arrested at its periphery. A sphere of the same 
specific gravity as water, however, passes through the curved tube 
with the greatest ease. A filtering action is thus exerted by the 
