BACILLUS MEGATERIUM 189 



cylindrical rods which are destitute of movement so long 

 as they are in zoogloea, but when isolated possess an extra- 

 ordinarily lively motility. The name Dispora was assigned 

 to the micro-organism from the fact that the protoplasm is 

 withdrawn to the ends, giving the rod the appearance of 

 being divided into two spores. By its vital action milk- 

 sugar is changed into glucose, upon which the yeast can 

 then begin to work. 



Examination op Other Articles of Diet 



Bacillus megaterium. — This bacillus was found by De 

 Bary on boiled cabbage-leaves. It consists of long, thick, 

 somewhat curved rods with rounded angles, frequently 

 connected in chains, and possessing slightly granular cell- 

 contents. The motion of the rods recalls the amoeboid 

 movements of cellular protoplasm. During involution the 

 shape of the rods loses its distinctness and malformations 

 occur, which, however, regain their normal outline on 



/ 



Chain with links containing spores 



Fig. 71.— Islet op Bacilius 

 Fici. 70.— Bacillus megaterium with megaterium on a Gela- 



Spohes. tike Plate. 



transference to fresh nutrient substances. Their sporu- 

 lation is particularly suitable for purposes of study, and the 

 spores also stain easily (fig. 70). On the gelatine plate 

 there form minute roundish colonies consisting of undulat- 

 ing filaments, which liquefy the medium slowly, and possess 

 a uniform or semilunar outline (fig. 71). A funnel-shaped 

 liquefaction appears in thrust-cultures, in which the bac- 

 teria sink to the bottom (fig. 72). On agar grey deposits 



