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chow. The latter held that the essential changes in inflamma¬ 
tion took place in the solid tissues outside of the blood-vessels. 
He maintained that the primary and chief effect of an inflamma¬ 
tory irritant is the excitation of the cells of a part to increased 
functional and nutritive activity, and that hypersemia and fluid 
exudations from the blood are secondary to this excitation. 
When Virchow made his investigation on inflammation, bnt 
little was known in regard to the migration or wandering powers 
of white blood corpuscles. He held that all cell elements present 
in inflammatory exudations were produced by proliferation from 
the pre-existing ceils, most frequently from connective tissue 
cells. 
In 1842 Dr. W. Addison described somewhat incompletely 
the passage through the walls of the blood-vessels of white blood 
corpuscles. 
In 1846 Dr. Augustus Waller described more fully the same 
phenomenon. Both these observers concluded that the escaped 
corpuscles became pus corpuscles. Their observations were but 
little noticed, and soon forgotten. 
Additional and important light on the pathology of inflamma¬ 
tion was obtained by Conheim, in 1867, when, he made investi¬ 
gations similar to those of Addison and Waller, which verified 
their observations and clearly established the fact of the emigra¬ 
tion of blood corpuscles during the process of inflammation. 
Conheitn’s experiments were made upon the frog, paralyzed 
by subcutaneous injections of curara. He caused artificial inflam¬ 
mation in transparent tissues, such as the web, tongue and mesen¬ 
tery of the frog. 
The first effect of an efficient irritant is dilatation of the 
arteries, and after a brief interval the veins and capillaries be¬ 
come similarly dilated. Dilatation of the arteries commences 
immediately after the application of an injury, and slowly 
increases for about twelve hours, and is “ accompanied by an 
increase in the length of the vessels, so that they become more or 
less tortuous.” At the same time the movement of the blood 
current is increased. This acceleration in the flow of blood 
seldom lasts more than an hour. The velocity of the current 
