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VI. Research on the Smallpox of Sheep. By E. Klein, M.D., Assistant Professor at the 
Laboratory of the Brown Institution , London. Communicated by John Simon, 
F.R.S., D.C.L., Medical Officer of the Privy Council and of the Local Government 
Board. 
Received June 11, — Read June 18, 1874. 
Description or Narrative of Experiments 215 
Anatomical Method 219 
Investigation of the Organisms contained in fresh Lymph by cultivation 220 
Anatomical Investigation of the Eruption ' 226 
A. Summary of previous Investigations 226 
B. Anatomical Peculiarities of the Skin of the Sheep 228 
C. Early Stage of the Development of the Primary Pustules 230 
D. Pustular Stage of the Development of the Primary Pustules 239 
E. Anatomical Investigation of Secondary Pustules 243 
Section I.— DESCRIPTION OR NARRATIVE OF EXPERIMENTS. 
Experiments with fresh Lymph. ■ 
Experiment 1. — Lymph sent by Professor Chauveau was used for the inoculation of a 
sheep on the 8th of December, 1878, in the following manner : — With the aid of a subcu- 
taneous Pravaz syringe an extremely small quantity was introduced into each of four 
punctures in the true skin of the groin on the right side and of five on the left side. On 
the morning of the 13th of December, two of the punctures in the groin on the right side 
and four of those on the left were discernible as surrounded by a small circumscribed 
areola, which projected somewhat above the general surface ; the puncture itself occu- 
pied the summit, and was marked as a brownish speck. 
On the morning of the 14th of December there appeared a new pock on the right, and 
in the evening of the same day one on the left side. They increased rapidly in size, the ' 
red hypertemic areolae becoming larger in breadth and in thickness. After the first two 
days of their appearance (that is, after the evening of the 15th December) they only 
became more elevated, i. e. thicker. 
As long as they increased in breadth they nearly all showed the central part most 
elevated ; but as soon as they ceased to increase in breadth, or shortly before that, they 
became depressed and at the same time pale in the centre, whereas the peripheral part 
seemed now to be very much elevated and red ; hence the line of demarcation between 
healthy and diseased skin was more marked than before. 
In this stage they presented themselves as large patches above the general surface, 
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