732 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
fine spirilla consisting of two or three turns, and the length of these 
was about 2 p. The author possesses one preparation over five years 
old, which still shows delicate spirilla quite clearly. These appearances 
were never seen in cultivation. 
Mechanism of the Virulence of Staphylococcus pyogenes aureus.* 
— Dr. H. Van der Velde records the results of a comparative study 
between an attenuated and virulent variety of Staphylococcus pyogenes 
aureus made on dogs and rabbits. 
From the experiments on rabbits, it was found that the virulence of 
Staphylococcus could be augmented by repeated passages through this 
animal, and that when attenuated and virulent cocci were injected into 
the pleural sac, the former lost and the latter gained in virulence. 
The attenuated cocci are more easily acted upon by the body juices, and 
by the leucocytes, than the virulent cocci, which secrete a special sub- 
stance. This, which causes the death of the leucocytes, is termed 
substance leucocide ” or leucocidine. It is destroyed by heating for 
ten minutes to 58°. 
Leucocidine is formed in artificial cultivations (bouillon) as well as 
in natural (blood-serum) without and within the body, and in equal 
quantity by virulent and non-virulent cocci. 
Besides leucocidine, the attenuated and virulent cocci secrete “ ly- 
sines,” which neutralize the bactericidal substance of the juices. 
Neither leucocidine nor lysine can be considered as special attributes 
of the virulent variety, they merely assist the infection. Virulence is 
to be considered as a greater or less tolerance on the part of cocci to the 
bactericidal substance of the juices. Increase of bactericidal power 
of the liquid part of the exudation probably depends on the white cor- 
puscles. 
With regard to dogs, the author found that both attenuated and 
virulent cocci were equally destroyed by the blood and serum, and that 
this animal reacted with the same intensity to both varieties. Repeated 
passages of cocci failed to increase the virulence. 
Manuals of Bacteriology. — Dr. L. Heim’s Text-book ofiBacteriologyf 
is a volume of 528 pages, illustrated by 138 plates and 50 photo- 
graphs. The work is divided into three parts, the first of which deals 
with bacteriological research in general, and the necessary apparatus 
and requisites. The second part treats of the biological and morpho- 
logical characters of Bacteria, and the third is devoted to bacteriological 
diagnosis. 
Dr. Bordoni-Ufireduzzi’s Manual of Bacteriological Technique f 
has recently reached its second edition, which is about twice the size of 
the first. Several new chapters, numerous figures, and eight chromo- 
lithographic plates have been added, while a special feature is a 
section dealing with the malaria parasite. 
* La Cellule, x. (1894) pp. 401-60 (1 pi.). f Stuttgart, 1894. 
+ Mailand, 1894. See Centralbl. f. Bakteriol. u. Parr.sitenk., xvi. (1894) pp. 384-8. 
