354 LANCASHIRE VETERINARY MEDICAL ASSOCIATION. 
the round cells surrounding fine capillary loops tinted red. The bright 
redness of granulation tissue is due to the blood shining through the 
transparent young cells. The tissue is very vascular. A granulating 
surface is not even and smooth, but presents minute granular or papil- 
ary eminences due to miniature heaps of the cells. Let us now inquire 
whence these young cells come ? Cohnheim made some interesting 
observations with the view of determining this point. I have spoken of 
the migration of white blood-corpuscles as illustrated in diagram No. 2. 
Cohnheim introduced aniline into the lymph sac on the back of a frog, 
and after cauterising the cornea of the animal, he found at the irritated 
spot, wandering cells exhibiting the aniline staining. He, therefore, came 
to the conclusion that the inflammatory cellular infiltration consists of 
emigrated white blood-corpuscles. 
It now remains for me to direct your attention to certain connections 
between granulations and the healing process. Let me recall to your 
recollection some of the chief naked-eye appearances which are observed 
in a gaping wound, or a wound attended with loss of substance. After 
the first twenty-four hours the margins are slightly reddened, somewhat 
swollen and sensitive to the touch, the same symptoms as in closed 
wounds. For the first day or two the surface looks grey and gelatinous 
with, perhaps, a trace of redness. Small fragments of dead tissue are 
adherent to the surface. On the third day the wound “ cleans off,’* and, 
if examined with a lens of low magnifying power, fleshy warts, or granu¬ 
lations are seen. For the few subsequent days the granulations become 
greatly developed, and the fluid flowing from the surface of creamy 
consistence presents the characters of pus already described, and in the 
words of the old authors —pus bonum et laudabile. 
The changes I have just enumerated are susceptible of great varia¬ 
tion, according to the size of the dead masses of texture, the loosening 
of larger masses requires a longer time, but the pathological process is 
in all cases the same, the line of separation exhibiting groups of small 
cells. In diagram No. 8, which illustrates the separation of a slough, 
you recognise by difference in colour the living textures below, the dead 
textures above, and in the boundary line between the two the active 
cellular elements which, by a process of absorption, loosen the dead from 
the living. I cannot do better than ask you to inspect the diagram 
No. 4, ‘which is taken from Billroth’s work on ‘ Surgical Pathology.’ 
A section of a granulating wound is shown, and, in order to bring out 
the distinctions between the pus and the granulation tissue cells, the 
former are represented as having been acted upon by acetic acid, and 
forming a layer on the surface of the granulation cells. You observe 
the capillary loops are tinted red, and groups of young cells are seen 
lying amongst them. 
From these remarks you will gather that pus is one of the products of 
granulation cells. When granulation tissue grows rapidly, owing to 
irritation or other causes, pus formation is more marked. Early in my 
paper I followed the mode of formation of abscess in connective tissue. 
May I ask you to compare the appearances presented by the so-called 
pyogenic membrane and the healthy granulating surface by reference to 
diagrams 4 and 5. The pyogenic membrane has the similar small-celled 
structure and the similar capillary loops. In the main the great practical 
difference is this, that the pyogenic membrane in the recent condition 
forms a complete retention sac, whereas the granulation surface of a 
wound is open. 
We naturally ask ourselves, How is it that an abscess continually 
grows larger by increase of contents ? Unless some foreign or dead body, 
