462 THIRD PART. BACTERIA OR SCHIZOMrCETES. 



germination for a considerable time, showing a remarkable degree 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 l 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 2 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 3 of it and requires further 

 investigation. 



1 NageU, p. 272. * See Van Tieghem in Bull. Soc. Bot. 26 (1879), p. 141. 



3 Cohn's Beitr. Ill, \\sfyf. 



