156 Proceedings of the Royallrish Acailemy. 
XXVI. — Repoet on the Eese arches of Peofessor Cohnheim on In- 
flammation AND Suppuration."^ By J. M. Purser, M. B. 
[Read May 8, 1871.1 
As the result of his researches on inflammation, Professor Cohnheim 
thinks the two following propositions are established : — 1. In an in- 
flamed part the white corpuscles of the blood pass through the walls of 
the vessels in great numbers, and, having become free in the tissue, 
constitute the cells of pus. 2. The cells of the inflamed part itself 
have no share in the formation of pus ; they persist for a time un- 
changed among the emigrated blood corpuscles, and if the inflammation 
last long enough, or attain a great intensity, they undergo a series of 
changes of a purely regressive or degenerative nature, ending in their 
death or destruction. 
On the first of these propositions I have already reported to the 
Academy. The discovery of the passage of the leucocytes of the blood 
through the uninjured walls of the vessels, first made by our dis- 
tinguished countryman, Dr. Augustus Waller, in 1846, and recorded 
in two papers in the Philosophical Magazine" for that year, excited 
little attention at the time ; and till the remarkable Paper of Professor 
Cohnheim was published in 1867, physiologists believed that all the 
cells found in the tissues, whether in the healthy or inflamed state, 
were formed there from Jiuids efl'used from the blood, either by a pro- 
cess of spontaneous generation (free cell formation) in this fluid or 
blastema, or by the division and multiplication of cells pre-existing 
in the part, and which were nourished by the efl'iised blastema. But the 
re-discovery by Cohnheim that the passage of blood corpuscles through 
the vascular walls could be seen, and that the whole process of emigra- 
tion could be watched and followed under the microscope, had the 
effect of disturbing the unanimity of opinion previously existing, and 
has given rise to a controversy as to the origin of pus corpuscles and 
other cells, which is still far from being settled. The great interest 
excited by the writings of Cohnheim has led to his experiments being 
repeated by numerous observers, and by these, with very few excep- 
tions, his results, so far as they relate to the emigration of the leuco- 
cytes, have been confirmed. 
In the Eeport already alluded to, I stated that on this point my 
observations were quite in accordance with those of Cohnheim, and since 
that Eeport was read I have many times repeated the experiments, and 
always with the same result. I have also had occasion frequently to 
demonstrate, to my pupils and others, the passage of the white corpuscles 
through the walls of the vessels. This phenomenon has been observed by 
* Ueber Bntziindung und Eiterung. Von Dr. J. Cohnheim, Archiv. f. path : 
Anat. Bd. XL. s. 1. Ueber das Verbal ten tier fixeu Bindegewebskdrperchen bei der 
Entziindung. Ibid. Bd. XLV, s. 333. 
