234 
DR. E. KLEIN ON THE SMALLPOX OE SHEEP. 
distended, interfascicular lymph-spaces, and especially the distended lymphatic vessels 
of the corium (in the lymphatic vessels of course with much greater distinctness), con- 
tained these filaments in very great numbers. In the more advanced stage of their 
development the individual filaments differ from each other considerably in size ; the 
branching is more distinct, so that they form a network. Each filament follows a 
course which is alternately curved and straight, so as to form more or less dense convo- 
lutions. The filaments are highly refractive, and appear to be of a greenish colour, 
which is the more distinct the thicker they are. Generally they appear perfectly smooth, 
even under a high power ; in some instances, however, I was able to see not only that 
they were composed of elongated joints, but also that it was possible to distinguish a 
surrounding delicate membrane and highly refractive greenish contents. The composite 
nature of the filaments is especially noticeable at the free ends ; here it can be distinctly 
seen that they are composed of joints. Towards the ends of the filaments these joints 
are short, elliptical, or spheroidal, becoming more and more elongated as their distance 
from the end increases; There are terminal filaments of a relatively great length, which 
are distinctly composed of spherical or elliptical joints. Other filaments occur which, 
at some point near the free end, possess one or more elliptical or spherical joints larger 
than the rest, or give off small lateral branchlets terminating in a similar manner. In 
the necklace-like filaments so formed it is sometimes observed that each of the spherical 
or elliptical bodies just mentioned appears to be enveloped by a delicate thin membrane 
(<?/. Plate 31. fig. 10, II., III., IV., & V., and Plate 32. fig. 11, A & B). 
In fig. 11 it will be noticed that the spherical bodies undergo [transverse division, 
thus forming dumb-bells and necklaces, and also that, by becoming elongated, they 
form the basis of the filaments. 
I think from the foregoing it can be stated with safety that we have to deal with the 
development of a fungus. It commences as a mass which corresponds in appearance 
to a mass of Micrococci (i. e. zooglcea) ; these grow into a mycelium, the constituent 
filaments of which differ very considerably from each other in thickness. The mycelium 
fructifies, forming conidia like an Oidium. The spherical spores proliferate by trans- 
verse division, forming thus smaller groups — dumb-bells and necklaces of smaller and 
smaller bodies. The conidia are, just like the filaments of the mycelium, highly 
refractive and of a greenish colour. 
The deeper stratum of the corium is the part in which the fungus is found chiefly in 
the earlier stages of the disease. 
Eventually the superficial stratum of the corium, as well as the superficial stratum of 
the subcutaneous tissue, is filled with them ; the former to a greater extent than the 
latter. As the natural direction of movement of liquid in the tissue is from the inter- 
fascicular or lymph-canalicular system into the lymphatics, and as the fungus is found 
in the latter as well as in the former, it might be expected a priori that the fungus, 
while increasing, would penetrate from the interfascicular channels into the lymphatics. 
That this is actually the case may be deduced from microscopic examination ; for it can 
