232 SUMMARY OF CURRENT RESEARCHES RELATING TO 



method ; spore formation was not observed. He gives details of the 

 cultural characteristics of this organism, and also a short account of the 

 morphology and life history of the mould, which, however, he cannot 

 identify with any hitherto described fungus. 



Bacillus subtilis group of Bacteria.* — F. D. Chester reviews the 

 researches of Oottheil and of Meyer, which show the value to be placed 

 on the morphological rather than on the cultural characters in making a 

 classification of this group of bacteria. 



The members of this group are arranged in two classes : (a) those 

 whose diameter is less than one micron (//,), B. mesenteric us, B. aste- 

 rosporus, B. subtilis, B. .simplex, and B. fusiformis ; {b) those whose 

 diameters exceed one micron, B. ruminatus, B. cereus, B. mycoides, 

 11. tumesc&ns, and B. megatherium. 



The principal value of measurements applies to the sizes of spores, 

 which are more constant; three sizes are included: (a) spores 0*5 /a— 

 0*6 fi in diameter, B. mesentericus • spores with an average diameter of 

 0*8 ai, B. cereus, B. tumescens, and B. fusiformis ; spores of 1 • /a-1 ■ 6 //. 

 diameter, B. megatherium, B. ruminatus, and B. asterosporus. 



Spores are further differentiated by their form and by the character 

 of their walls. Five different forms are noted : (a) reuiform spores of 

 B. megatherium ; (b) small elongated spores of B. mesentericus ; (c) 

 quadrangular and pointed forms in B. ruminatus ; (d) round spores in 

 B. fusiformis, and (e) the oval or elliptical spores of other species. 



Spores stained by his method show two distinct parts, an inner un- 

 stained central body, and an outer deeply-stained wall or membrane. 

 In some varieties (B. subtilis) this wall is thin and without differentia- 

 tion of parts ; in others (B. ruminatus) it is a relatively thick capsule 

 composed of three distinct portions, an outer deeply-staining membrane 

 (extine), a delicate inner layer (intine) surrounding the central body, 

 and an intermediate faintly-staining portion. 



Germination in this group takes place in two ways — by protrusion, 

 and by stretching and subsequent rupture. Spore germination is either 

 polar or equatorial, and sometimes the germinal rod emerges from the 

 rod from both poles, the spore membrane remaining attached to the 

 rod as a ring (B. simplex). When the germinal rod emerges from 

 the spore it enters the " vegetative " stage ; these vegetative rods 

 undergo septation, forming shorter vegetative cells, and these, again, 

 produce short and long chains or individual swarms. The duration 

 of the swarming stage and the character of the motility have an im- 

 portant bearing on the differentiation of these organisms, and also on 

 certain cultural characteristics. The vegetative and swarming stages 

 are followed by the production of longer vegetative rods, and their 

 separation as individual cells whose special function is to produce spores. 

 These specialised cells have been termed " sporangia." He gives details 

 of the cultural features and chemical functions of the group, and 

 appends a classification. 



Bacillus fusiformis.t — ■ V. Ellermann has isolated this organism on 

 two occasions — from a fatal case of necrotic stomatitis, and from a 



* Centralbl. Bakt., 2 ,e Abt., xiii. (1904) pp. 737-52. 

 t Op. cit., l*a Abt., xxxvii. (1904) p. 729. 



