1895.] The Etiology of Small-Poz. 701 
16-32 hours of cultivation, aggregated in masses, afterwards in 
films the formation of which seemed to be the terminal phase 
of their life-history." Cohn named this organism Microspheria 
vaccine which was a specific coccus and no representative of 
some stage of development of some otherorganism. Thename 
was later changed into Micrococcus vaccine which Cohn, in his 
system of bacteriology, described in the following way”: “ Cells 
ball-shaped, 0.5-0.75 ». in diameter, or united two and two or 
more in chains and masses, also forming a zoogloea. In fresh 
lymph from cow-pox and small-pox as well as in the pustules 
in confluent variola.” 
Weigert, a short time before Cohn, found™ “ vessel-shaped, 
irregular, often ramified formations of 0.1-0.2 mm. in diameter 
with granulated, well-marked contents which was not affected 
by acetic acid, sodium and glycerin. He interpreted these 
formations as lymphatics filled with bacteria. They were 
found in the neighborhood of small-pox pustules, and at their 
edges, where also haemorrhagical herds, and arteries with the 
same contents were observed. Cohn declared that Weigert’s 
granules were identical with his Microspheria. 
Thus it was beyond doubt that vaccinia, cow-pox and vari- 
ola were caused by attacks of bacteria. Burdon-Sanderson 
also confirmed this view. The history of the cases also show 
that the disease is caused not only by a contagium fixum, but 
also by a contagium halituosum. 
Weigert’s observations concerning the lymphatics were 
repeated and confirmed by Klein.“ 
Klebs” set forth the statement that the organism (microcci) 
in vaccinia and variola exhibit peculiar physiological and 
morphological properties. The cells are placed four and four 
together and assume, ontogenetically, no other shape than that 
1 The same aggregations had been observed by Keber. 
12 Beitr. zur Biol. d. Pflanzen, Vol. I, part Il, 161. 
13 Ueber Bakterien in der Pockenhaut. Centralbl. f. d. med. Wiss. IX, 606- 
611, 1871. Ueber pockenaehnl. Eruptionenininnern Organen, Deutsche Zeits- 
chrift f. prakt. Med. I, 367-369, 1874. Anatom. Beitr. z. Lehre von den Pocken, 
part I, 1874. 
14 Phil. Trans. Lond., 1874; Micro-Organism and disease, 1886, 69. 
13 Arch. f. experiment. Pathol. und Pharm. X, 222, 1879. 
