320 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
spotted over with dark-green patches which later on become brown or 
orange-brown. In the severer cases, especially from artificial iufection, 
the leaves become malformed and monstrous. In some of the experi- 
ments the absence of chlorophyll was noted, and this defect was found 
to be due to the association of a bacterium, Bacillus agglomerans , w r ith 
the virus. 
The author concludes his interesting observations by alluding to 
other infectious diseases of plants due to a contagium fluidum. 
Immunity to Arsenic Compounds.* — Dr. Besredka’s second memoir 
on immunity to arsenic compounds deals with the leucocytic reactions in 
the different forms of arsenical intoxication, and with the faculty 
possessed by the white corpuscles of englobing or rather of absorbing 
the arsenic injected in a soluble condition. The reactions of the leuco- 
cytes vary according to the resistance of the animals, and therefore 
with the dose of the poison and with the accustomedness or non-accus- 
tomedness of the animal to the poison. 
The injection of arsenic is always followed by hypoleucocytosis, and 
this, if the animal survive, by hyperleucocytosis. There is no hyper- 
leucocytosis, or only a transitory and abortive one, if the dose be fatal. 
Chemical analysis of the leucocytes shows that they contain arsenic only 
when the animal survives. Hyperleucocytosis or positive chimiotaxis is 
associated with englobement or absorption of the poison and by survival 
of the animal. Therefore there exists, in regard to a soluble toxic pro- 
duct, a phagocytosis having exactly the same character as for microbes 
or insoluble poisons. 
Soil Bacillus of the Type of B. megaterium.j — Mr. C. AY. Sturgis 
isolated from clayey and gravelly soil a bacillus 3 * 4-7 * 7 /x X 1 * 2-1 • 5 p. 
It occurs as isolated rods or as long chains. Though normally aerobic, 
it is a potential anaerobe. It has a preference for acid media, and in 
media containing carbohydrates a thick firm gelatinous sheath is formed. 
Gelatin is liquefied. The temperature limits are from 10° to 35° C. It 
peptonises milk without coagulating it. On agar the growth is flat, 
circular, tawny in colour, and emits an odour like melted glue. Spores 
are produced in 22-70 hours, according to the temperature and the 
medium. The cytoplasm condenses at one pole, and there produces a 
spore 2-2 * 8 p x 0 * 8-1 p. The spore germinates at one end in a direction 
parallel to the longer axis. The subsequent growth of the chains is 
intercalary as well as terminal. 
The long forms are non-motile, while the rods and short chains, 
especially when young, and at temperatures between 23° and 33 ^exhibit 
lively movements. 
Involution forms arise in old cultures, or in those made at low 
temperatures. The organism is non-pathogenic, does not produce gas 
or pigment, and stains readily with carbol-fuchsin, gentian-violet, or by 
Gram’s method. 
Micrococcus zymogenes.f — Mr. W. G. MacCallum and Mr. T. AY. 
Hastings found a hitherto undescribed micrococcus in a case of acute 
* Ann. Inst. Pasteur, xiii. (1899) pp. 209-24. Cf. this Journal, ante , p. 197. 
t Proe. Roy. Soc., lxiv. (1899) pp. 340-2. 
tfiCentralbl. Bakt. u. Par., l te Abt., xxv. (1899) p. 384. 
