SPORES 31 



liquid cultures, spore-formation is sometimes very active after twenty- 

 four hours. Again, if the conditions are not favourable, it may be 

 postponed for several days, when spores will be found in greatly 

 reduced numbers, as the majority of the individuals, under un- 

 favourable circumstances, seem to have lost the capacity of producing 

 them. 



Not much can as yet be said with regard to the germination 

 of spores belonging to the order Coccaceae. The spores of Sarcina 

 ureae are round and possess two coats, the inner thin, the outer 

 thick, resistant and studded on the outside with six or seven 

 blunt points (Fig. 48). During germination the spore first loses its 

 highly refractive appearance as a result of the swelling which it under- 

 goes. Fig. 48 shows the subsequent changes that take place. The 



FIG. 48. Germination of spore of FIG. 49. Types of germination. 



Sarcina urea. 



outer membrane is burst open and the contents emerge clothed in the 

 inner membrane. The young coccus, after freeing itself from the outer 

 spore-coat, increases in volume, and surrounds itself with a more sub- 

 stantial outer membrane (Fig. 48c). In some cases division rapidly 

 follows, as seen in Fig. 48d, where the outer spore-coat is still in the 

 immediate neighbourhood. The time required for germination is the 

 same as for bacillus-spores, viz. between four and six hours. 



With regard to the genus Spirillum, spore-formation and spore- 

 germination have been recorded, but neither process has since been 

 observed, and the figures are not trustworthy, so until the results of 

 more accurate research are forthcoming, we must withhold our judgment 

 as to whether the spiral bacteria form spores. 



Spore Germination. We have seen that an endospore has two 

 coats. In germination the outer is left behind, but the inner 



