SPORE-FORMATION IN THE DISPORIC BACTERIA. 595 
Zettnow, E. (1908).—‘“ Ueber Swellengrebels Chromatinbinder in 
Spirillum volutans,” ‘CB. Bakt. Parasitenk,’ I Abt., xlvi, 
p. 195. 
Zopf, W. (1883).—* Die Spaltpilze,” Breslau. 
DESCRIPTION OF PLATE 13, 
Illustrating Mr. C. Clifford Dobell’s paper ‘‘On the so-called 
‘Sexual’ Method of Spore-formation in the Disporic 
Bacteria.” 
[All figures are from preparations fixed with formalin and stained by 
a modification of Giemsa’s method. Drawings made under a Zeiss 2 mm. 
homog. oil immersion apochromatic, comp.-oc. 12. Magnification ca. 
2000 diameters. | 
Figs. 1—19. Bacillus spirogyra. 
Fig. 1.—An individual with an almost straight nuclear filament. 
Fig. 2.—An individual with well-marked spiral or zig-zag filament. 
Fig. 3—An individual in which the filament is very greatly con- 
torted. 
Figs. 4, 5.—Two burst individuals, in which the filament is clearly 
seen to be a solid independent structure lying in the cell. 
Fig. 6.—Division of an individual with a straight filament. 
Figs. 7—16. Stages in spore-formation. 
Figs. 7, 8, 9.—Stages in division of a large individual into two. 
Fig. 10.—Small individual formed by division of a large one—about 
to form a spore. 
Fig. 11.—A similar organism at a later stage. One end of the 
filament is much enlarged, forming the spore-rudiment. 
Fig. 12.—A later stage, in which the spore-rudiment is further deve- 
loped. 
Fig. 13—An abnormal case, in which a large individual has not 
completely divided, and in which each of the (still attached) daughter- 
individuals contains a spore-rudiment similar to Fig. 11. 
Fig. 14.—Stage succeeding Fig. 12. The spore-membrane has just 
been formed, and is stained a bright blue. 
Figs. 15, 16.—Later stages—completion of spore-formation. In 
Fig. 16 the spore is fully formed, and the remains of the cell are break- 
ing up. 
VOL. 53, PART 3. 
NEW SERIES. Al 
