462 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
scissipara g. et sp. n. It occurs in the form of naked spherules of proto- 
plasm, varying between 12 and 27 p in diameter, propagating only, as 
far as has been observed, by division. This takes place after the 
spherule has invested itself with an enveloping membrane, the internal 
protoplasm sometimes clothing itself with a membrane after division 
while still within the original envelope. 
Bacterial Diseases of Plants. — Mr. Erwin F. Smith* * * § gives further 
details of the brown rot of cabbage caused by the attacks of a Schizomy- 
cete. The greater part of the infection takes place through water-pores. 
The disease is frequently disseminated by insects. The wild mustard 
(of America), Brassica sinapistrum , is one of its common host-plants. 
A disease of the sugar-beet has recently appeared in the United 
States closely resembling that described (in Europe) by Kramer and 
Sorauer, caused by Bacillus Betse. 
Mr. H. L. Russell | gives a full account of the life-history of Bacillus 
campestris, and of the nature of the ravages produced by it in the cabbage- 
plant ; also of the best modes of combating it. 
Spread of Infectious Diseases by Biting Insects Dr. G. EL F. 
Nuttall, who had made experiments bearing on the question of the 
dissemination of plague by flies, records the result of researches on the 
part played by biting insects in the spread of infectious diseases. For 
this purpose mice, dead or dying of anthrax, fowl cholera, or mouse 
septicaemia, were allowed to be bitten by hungry bugs and fleas. With 
the juices from these the animals were infected. All the experiments 
were negative, that is to say, none of the animals sickened. Culture 
and inoculation experiments, and microscopical examination of the con- 
tents of the insects, showed that the infective agent is rapidly destroyed 
within the body of the insect, and that this germicidal action is more 
potent at high temperatures. 
The suggestion is thrown out that if biting insects disseminate in- 
fectious disorders, this is effected by the host infecting himself by 
scratching or rubbing in the virus after squashing the insect. 
Effect of High Pressures on Micro-organisms.§ — Sig. G. Malfitano 
made a large number of experiments with pure cultures of bacteria, fungi, 
&c., for the purpose of ascertaining the effect of exposure to high pres- 
sure for various lengths of time. The micro-organisms were exposed to 
pressures ranging between 25 and 60 atmospheres for 20 to 64 hours. 
Among those destroyed were B. coli com., B. anthracis , B. prodigiosus , 
typhoid and cholera bacilli, and some of the pyogenic cocci ; while 
B. subtilis, B. mesentericus, Tyrothrix , and B. cedematis invariably sur- 
vived. The length of exposure appeared to have more influence than the 
degree of pressure. On B. subtilis the interrupted action of compressed 
carbonic acid gas for 20 hours, four times repeated at intervals of 
24 hours, had no effect. The vitality of the spores of B. subtilis was 
unaffected by liquefied carbonic acid gas. 
* Bot. Gazette, xxv. (1898) pp. 107-9. Cf. this Journal, 1897, p. 574. 
t Univ. Wisconsin Agric. Exp. Stat., Bull. No. 85, 39 pp and 15 figs. 
% Centralbl. Bakt. u. Bar., l te Abt., xxiii. (1898) pp. 625-35. Cf. this Journal, 
1897, p. 577. 
§ Boll. Soc. Med.*Chir. di Pavia. See Nature, lvii. (1898) p. 614. 
