462 THIRD PART.—BACTERIA OR SCHIZOMYCETES. 
germination for a considerable time, showing a remarkable depree of resistance to 
the effects of desiccation, extreme temperatures and the like (see section CXXXIV).. 
Germination commences as soon as the spore is subjected to the conditions 
required for the nutrition and vegetation of the species, that is, as soon as it is placed 
in a suitable nutrient solution at a proper temperature. It is completed in a few. 
hours when the conditions are favourable, and consists chiefly in the development 
of the spore into a cell which assumes all the characters of the parent-cell as regards 
conformation and vegetation. The spore at first enlarges in size, loses its high 
refringent power and becomes pale and turbid, like a bacterium-cell when in an active 
state of vegetation; it then elongates and assumes the shape characteristic of the 
species and at once begins to divide like the vegetative cell, and locomotion may 
commence at the same time. When the elongation has reached a certain small 
amount, which is moreover different in different individuals, a membrane dividing 
usually into two regular valves of equal size is seen in most cases to separate 
gradually from the growing cell, being evidently raised off from it by the hyaline 
gelatinous outer layer of the membrane of the growing cell. The valves are usually 
thin and pale-coloured; but in Bacillus subtilis they have nearly the same amount 
of refringent power as the ripe spore, so that it is probable that the latter owes its 
characteristic appearance to the membrane which is thrown off in germination. The 
pieces of the detached membrane gradually disappear in the surrounding fluid. In 
spores which have elongated in the direction of the longitudinal axis of the mother- 
cell the membrane splits in the same or in the transverse direction. The direction. 
varies with the species; the membrane for example of Bacillus butyricus according 
to Prazmowski, and of other species, parts longitudinally, that of Bacillus subtilis 
transversely. 
The membrane. is not thrown off in the above manner in all cases in germi- 
nation, but is sometimes seen to swell up and finally disappear. I observed this 
repeatedly in Bacillus Megaterium and Buchner? saw it in the Bacillus of anthrax. 
The direction of growth in length of the vegetative cell first developed from 
the spore in relation to the longitudinal axis of the spore or its mother-cell is the 
same in all observed cases as that of the spore, whether the spore-membrane bursts 
longitudinally or transversely, or swells up and disappears. This is the case also 
with Bacillus subtilis, as will be described hereafter at greater length, where according 
to Brefeld and Prazmowski the first cell usually issues transversely at right angles 
to the longitudinal axis of the spore from the spore-membrane which has burst 
on one side. 
The above is the course of development observed especially by Brefeld, Van 
Tieghem? and Prazmowski in many of the species which contain no chlorophyll. It 
occurs also in. Van Tieghem’s species containing chlorophyll which have been 
mentioned above. In these the chlorophyll disappears during the formation of the 
spores and reappears in germination. Whether the bacterium of blue milk is one 
of this kind is still uncertain after Neelsen’s account? of it and requires further 
investigation. 

1 Nägeli, p. 272. * See Van Tieghem in Bull. Soc. Bot. 26 (1879), p. 141. 
3 Cohn’s Beitr. III, Heft 2. 
