98 PROGRESS OF MICROSCOPICAL SCIENCE. 



Dr. Carter is knoTvn to be ; but wheu we find a doctrine, wliicli we 

 believe to be altogether erroneous — the result of a misinterpretation of 

 microscopic appearances — used by men of eminence (who themselves 

 may not have the opportunity or possess the special training necessary 

 for this i)articiilar branch of study) as a basis ujion which to found the 

 etiology of other diseases, we feel that the time has arrived for giving 

 free expression to our opinion regarding it." 



On the Smallpox of Sheep. — Dr. E. Klein, Assistant Professor at the 

 Laboratory of the Brown Institution, in a paper read before the Eoyal 

 Society in June, 1874, says that Variola ovina, or smallpox of sheep, 

 is a disease which, although it is not communicable to man, and 

 possesses a specific contagium of its own, very closely resembles human 

 smalljiox, both as regards the development of the morbid process and 

 the anatomical lesions which accompany it. This correspondence is 

 so complete, that it cannot be doubted that the pathogeny of the two 

 diseases is the same. The present investigation was therefore under- 

 taken in the confidence that the application of the experimental method 

 to the investigation of the ovine disease would not only yield results 

 of value, as contributory to our knowledge of the infective process in 

 general, but would throw special light on the pathology of snialli)ox. 



The paper consists of four sections. In the first, the author gives 

 an accoimt of his experimental method, which consisted in communi- 

 cating the disease by inoculation to a sufficient number of sheep, and 

 in investigating anatomically (1) the pustules produced at the seat of 

 inoculation, and (2) those constituting the general eruption. The 

 lymph employed was obtained by the kindness of Prof. Chauveau, of 

 Lyons, and Prof. Cohn, of Breslau. 



In the second section, the organisms contained in fresh lymph, and 

 the organic forms derived from them by cultivation, are described. 

 The author finds that fresh lymph contains spheroidal bodies of 

 extreme minuteness, which correspond to the micrococcus of Hallier 

 and to the spheroids described by Cohn and Sanderson in vaccine 

 lymph. It also contains other forms, not previously described, which 

 in their development are in organic continuity with the micrococci. 



The third section contains a complete anatomical description of 

 the skin of the sheep with special reference to those particulars in 

 which it differs from that of man. 



The remainder of the paper is occupied with the investigation of 

 the changes which occur in the integument at the seat of the inocula- 

 tion, and with tlie anatomical characters of the secondary pustules. 



The most imi)ortant results are the following : — 



1. The develojiment of the primary pock may be divided into 

 three stages, of which the first is characterized by progressive thicken- 

 ing of the integranent over a rapidly increasing but well-defined area ; 

 the second, by the formation of vesicular cavities containing clear 

 liquid (the " cells " of older authors) in the rete Malpighii ; the third, 

 by the impletion of these cavities with pus corpuscles and other 

 structures. It is to be noted that the division into stages is less 

 marked than in human smallpox. 



2. The process commences in the rete Malpighii and in the sub- 



