ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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splenic tumidity, and parenchymatous nephritis. The toxin, which is 
prepared by simply filtering broth cultures 24 days old, when injected 
into some animals, gives positive results, and in man reproduces typical 
yellow fever (amarillism). The toxin is scarcely affected by heating to 
70°, though boiling sensibly attenuates it. The toxic power of cultures 
sterilised with ether is markedly increased. Bacillus icteroides, as the 
organism is named, is able to live on or in company with Hyphomycetes. 
This remarkable feature is easily demonstrable in cultures which are 
apparently quite dead. 
Dr. Havelburg * has found in the contents of the stomachs of persons 
dead of yellow fever at Rio de Janeiro a bacillus 1 fx long and from 0*3- 
0*5 fx broad. It is easily stained, but not by Gram’s method. It grows 
easily on gelatin, which is not liquefied. The growth is white on gelatin, 
and also on agar. Bouillon becomes turbid in 24 hours, with the forma- 
tion of a grey cloudy sediment. Saccharated media are fermented, with 
the formation of gas. Milk is coagulated in 24 hours. 
Parasites of Vaccinia and Variola, f — M. P. Salmon infers, from his 
researches into the nature of the infective agent of vaccinia aud variola, 
that the appearances observed by himself and others merely simulate a 
parasite, and that this pseudo-parasite is nothing but a ball of chromatin 
more or less condensed and of no particular form. The pseudo-parasite is 
not of endogenous, but of extra-epithelial origin, being derived from the 
migratory polynuclear leucocytes, the nucleus of which becomes trans- 
formed into the vaccinia granules. A table giving the colour reactions 
of the epithelial cell, the parasitic corpuscles, and the polynuclear 
leucocyte, shows that the two latter bodies invariably exhibit identical 
colour appearances, and that the nucleole of the epithelial cell not 
infrequently corresponds. 
* Lancet, 1897, ii. pp. 59-60 ; and Ann. Inst. Pasteur, xi. (1897) pp. 515-22. 
f Ann. Inst. Pasteur, xi. (1897) pp. 289-307 (1 pi.). 
