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corresponded with the heat necessary for the growth of the first blood- 
vessels in the egg. Blood-vessels of the embryo were destroyed by 
the gentlest handling ; so likewise the new vessels of a healing sore 
bled by the lightest touch. 
In the embryo, colourless elements of blood constituted the first 
vessels ; so, also, the new vessels of healing parts. All parts of the 
embryo were more yascular than afterwards when growth was further 
advanced ; so with healing parts, granulations were, at first, more 
vascular than they were when turning into fibrous-tissue. It took a 
longer time to repair a broken bone than it did to repair a ruptured 
tendon, and longer to repair a ruptured tendon than a wound in the 
skin, because, in embryo growth, tendons were completed later than 
skin, and bones later than tendons. Thus, healing was shewn to bea 
department of Natural History. 
Tt was well known that inflammation preceded granulation ; what 
had it to do with healing? When fully formed, blood-vessels were 
called upon to contribute to healing ; a change took place in their coats 
from elastic fibrous to fragile globular tissue—a kind of retrogression 
to the embryo state. The change might be said to do them violence, 
as it altered their state of cohesion and elasticity to one of fragility. 
Hence the pain of inflammation, demanding quiescence in parts pre- 
paring for healing. New blood vessels for reparation could not possibly 
partake of the circulation without this change in the coats of the ex- 
isting vessels. At the commencement of inflammation blood had been 
seen depositing its colourless globules upon the interior of the vessels ; 
these globules, or cells, gradually accummulating, at length interposed 
between the stream of red blood and the elastic coats of the vessels, 
and substituted a fragile globular tissue for the fibrous one. Vessels 
so altered were virtually embryonic, prepared to set off new vessels 
and new growths. Inflammation was the necessary preliminary to heal- 
ing by granulation. 
The two main constituents of the body were the solid parts of 
the blood. Injury to blood was just as fertile a source of inflammation 
as injury to the solid parts. 
In external parts we could see the antecedents of injury, as dust 
in the eye, a thorn in the finger, a bullet in the side, &c. ; and the 
form, magnitude, and extent of inflammatory action was measured by 
the triviality or gravity of the damage done. But in all that related 
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