DR. E. KLEIN ON THE SMALLPOX OE SHEEP. 
231 
the corium are somewhat distended ; in the small veins and capillaries the endothelium 
is seen with much greater distinctness than in those of the healthy tissue. Especially 
in transverse sections through small veins and capillary blood-vessels it is found that the 
endothelial cells are swollen, distinctly granular, and their nuclei enlarged. Accordingly 
the wall of these blood-vessels appears thicker and altered. This is in so far an 
interesting fact, as Cohnheim, by the aid of experiments (see his latest researches on 
Inflammation, Berlin, 1878), arrived at the conclusion that the walls of the blood-vessels 
must necessarily in inflammation undergo some changes to cause the exudation of the 
fluid and the formed parts of the blood, which, as is well known, represent very material 
morphological symptoms in inflammation. 
The tissue of the corium in general is slightly oedematous, the interfascicular spaces, 
i. e. lymph-canalicular system, being larger and more clearly visible than in the normal 
condition. The connective-tissue corpuscles, situated in the interfascicular system of 
spaces, are recognizable at the same time in many places, their nuclei being more distinct 
than in the normal parts. In the interfascicular lymph-canalicular system of the 
corium, chiefly where the blood-vessels are more numerous, e. g. around the glands, 
there are found lymph-corpuscles, which are the more numerous the nearer one 
approaches to the blood-vessels ; this fact enables us to say that they are probably all 
extravasated colourless blood-corpuscles. Whereas the lymphatic vessels of the corium 
are hardly to be found in the corium of healthy skin after simple hardening, they 
are in our case easily traced, being distended and more or less filled with a transparent, 
homogeneous or finely granular substance, which in all its appearances resembles 
coagulated plasma. 
The changes of the subcutaneous tissue are similar, only much slighter ; they diminish 
more and more towards the depth. We have therefore only such changes as one 
might expect in inflammation in the strictest sense of the word, viz. distended blood, 
vessels, altered walls of blood-vessels, exudation of plasma, and extravasation of colourless 
blood-corpuscles, seen in the distended lymph-canalicular system and distended lymphatic 
vessels. The greater distinctness of the connective-tissue corpuscles and the enlarge- 
ment and greater transparency of the rete Malpighii are probably due to the increased 
irrigation of the tissue with exuded plasma. 
If we direct our attention to the pocks that have been cut out twenty-four hours after 
they made their appearance, we find the changes above stated much more marked. 
The rete Malpighii is still thicker, more transparent, the nuclei of the epithelial cells 
of the deeper strata enlarged, many of them in the act of division or already divided ; the 
papillae and the corium in general more oedematous than in the former case, the lymph- 
canalicular system being not only. very marked and distended, but containing a finely 
granular material — coagulated plasma. Further, the infiltration of the corium with 
lymph-corpuscles has increased, it being now possible to trace the course of these bodies 
from the larger branches of the blood-vessels of the corium into the distended lymph- 
canalicular system. The connective-tissue corpuscles of the oedematous corium appear 
2 i 2 
