352 LANCASHIRE VETERINARY MEDICAL ASSOCIATION. 
white blood-corpuscles, and in lymphatics as lymph-corpuscles, present 
characters closely resembling pus-cells. 
Secondly.—Connective tissue, bone, and cartilage, consist of cellular 
and intercellular elements, the former are granular nucleated masses of 
protoplasm with or without branches, known in connective tissue as 
connective-tissue corpuscles, in cartilage as cartilage cells, and in bone 
as osseous corpuscles. In addition to these, in the fixed or stationary 
corpuscles, there exists in connective tissues certain cells named wander¬ 
ing cells, first described by Recklinghausen. The so-called wandering 
cells are identical with blood- and lymph-corpuscles. 
Thirdly.—There are also entering into the formation of skin and 
mucous membranes cells constituting a distinct layer on the surface, 
known in the skin as epidermis, and in mucous membranes as 
epithelium. 
Fourthly.—The cells occurring in the various glandular organs forming 
the actively secreting or excreting elements, in many cases of the 
epithelial type, should be enunciated amongst groups presenting some 
points of resemblance to pus-cells. 
In 1876 Professor Cohnheim, of Berlin, minutely described the process 
of emigration of leucocytes or white blood-corpuscles. In the diagram 
No. 2, which is copied from one by Dr. Caton in the Journal of Anatomy 
atid Physiology , 1871, a blood capillary and small veins are represented, 
and you observe the white blood-corpuscles in contact with the walls of 
the vessels; some of them with small processes, others with larger pro¬ 
cesses, piercing the wall uutil at last the whole corpuscle becomes extra 
vascular. Thus we have introduced into inflamed tissue cellular emi¬ 
grants from the blood-vessels. 
Although two Englishmen, Dr. Addison, in 1842, and Dr. Augustus 
Waller, in 1846, had detailed similar phenomena, it was not until after 
Cohnheim’s investigations that this migratory process occupied an im¬ 
portant place in pathology. 
Inflammation of connective tissue tending to suppuration has been 
long known as phlegmonous inflammation. Direct anatomical exami¬ 
nation has disclosed certain naked-eye characters presented by the 
affected part when superficial, but to these I need not do more than 
cursorily allude, such as swelling, redness, &c. Microscopic investiga¬ 
tion has shown that the cells increase in number at the expense of the 
fibrillar intercellular substance, which gradually disappears. 
This diagram, No. 3, will render the formation of abscess in connec¬ 
tive tissue more clear. You notice that the young cells are collected 
in patches corresponding to the site of the original connective-tissue 
corpuscles, and that in the middle of the drawing the smaller collections 
have become fused. It can be readily seen how these groups may extend 
irregularly in their circumference. 
Formerly Virchow, in his cellular pathology, asserted that the groups 
of pus cells were produced by the multiplication of the previously 
existing connective-tissue corpuscles, but, taking into consideration 
Cohnheitn’s researches, we can now assert that many, if not all, of these 
cells are leucocytes escaped from the blood-vessels of the tissues. I may 
here allude to the circumstance, of which I shall speak more fully here¬ 
after, that by artificial injection capillary vessels have been shown to 
exist in the form of loops around these collections. Thus is demon¬ 
strated the practical fact that the pyogenic membrane of the older 
writers consists of the circumferential layer of young cells or leucocytes 
lying amongst loops of capillaries. By the aid of diagrams 4 and 5, you 
may gather more clearly what I wish to convey. The pyogenic mem¬ 
brane,^ short, consists of granulation tissue. 
