ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 87 



and spirally twisted, the number of turns varying from a quarter turn 

 up to fifteen or more turns ; the width varies from 1-6 p, the length 

 reaching 200 /x or more ; the middle portion of the cell has a thickness 

 of only about 0*25 fx, whilst the edges are thickened up to 0*5 /x ; there 

 is no definite membrane ; the ends are irregular and unsymmetrical ; 

 conidia formation takes place as in the two previous organisms ; only 

 one doubtful case of vegetative division was observed. Referring to the 

 layer of iron on the membrane that surrounds these organisms, the 

 author considers it to be an instance of the property possessed by 

 vegetable protoplasm of attracting certain non-living substances, and he 

 repudiates the idea that the attraction of the iron has any biological 

 significance. 



Susceptibility to Plague of Rats of Diverse Races.* — E. Klein 

 has found that the common sewer rat is considerably less susceptible to 

 plague than the tame or white rat. Experimenting on the brown and 

 grey ship rat from South America, the brown and white ship rat from 

 Norway, and the black rat from New Zealand, India, and South Africa, 

 the author found that cultures of white rat B. pestis are by far the most 

 virulent ; next comes B. pestis of the black rat ; but the B. pestis 

 obtained through the brown South American ship rat and the Norway 

 rat was in each case of lesser virulence. 



Staphylococci Pathogenic to Man.j — F. W. Andrewes and M. H. 

 Gordon, for purposes of differentiation and classification, have subjected 

 a large number of staphylococci, obtained from various sources, to a 

 series of observations, which included besides those dealing with morpho- 

 logical, tinctorial, and cultural characters, eight physiological tests, viz. 

 (1) the clotting of milk within one week at 37° C. ; (2) the liquefaction 

 of gelatin within one week at 22° C. ; (3) the reduction of neutral red 

 within 48 hours at 37° C. under anaerobic conditions ; (4) the reduction 

 of nitrate to nitrite within three days at 37° C. ; (5) the production of 

 acid when cultivated for one week at 37° C. in Lemco-litmus medium 

 containing 1 p.c. maltose ; (6) ditto with lactose instead of maltose ; 

 (7) ditto with glycerin ; (8) ditto with mannite. 



The authors conclude that staphylococci fall into two groups : 



(1) Gram-negative cocci (M. catarrhalis, meningococcus, gonococcus) ; 



(2) Gram-positive staphylococci, of which 8. pyogenes is the commonest 

 example. It exists either as S. aureus, S. citreus, or *S'. albus, according to 

 the partial or complete suppression of its chromogenic properties. The 

 common saprophytic coccus of the skin, S. epidermidis albus, is perfectly 

 distinct biologically, and is identical with the Micrococcus neoformuns of 

 Doyen. 



Micrococcus of Epidemic Cerebrospinal Meningitis. | — M.H.Gordon 

 reviews the evidence associating the meningococcus of Weichelbaum with 

 epidemic meningitis. The organism is found to be present in pure 

 culture both in the cerebrospinal exudate and in the cerebral ventricles ; 

 the coccus, which is negative to Gram's stain, is in the form of flattened 



* Rep. Med. Officer Local Govt. Board, 1905-6, p. 431. 

 t Tom. cit., p. 543. X Tom. cit., p. 435. 



