1 8 Lectures on Bacteria. [^ ii 



begins to be formed is marked by the absence of granulos 

 This spot looks in solution of iodine like a notch of a pa 

 yellowish colour, occupying one extremity of the rod whic 

 elsewhere tends to be blue, and is moreover distinguished I 

 its lower power of refraction even before the use of a reager 

 As the spore grows in size the granulosa disappears. Accor 

 ing to Prazmowsld the granulose is not always present befo: 

 the formation of the spore, even in Bacillus Amylobacter. ] 

 other Bacilli, the three, for example, just previously named, 

 has never been observed ; their protoplasm either remains ui 

 changed before spore-formation, or at most becomes a litt 

 less transparent and in . larger forms more evidently fine 

 granular. 



A mother-cell, so far as can be positively stated, never pn 

 duces more than a single spore. This can be determined wi 

 certainty in almost all cases, and the few accounts which ha^ 

 been given of the formation of two spores in a single cell a 

 doubtful, being unaccompanied by any guarantee that tl 

 boundaries of adjoining cells have not been overlooked i 

 errors of other kinds admitted. I must, however, add that i 

 exception to the prevailing rule has recently come under n 

 own observation in the case of a species nearly allied to Bacilli 

 Amylobacter (see Lecture IX), which usually follows the rul 

 but does also sometimes contain two spores in a cell which h; 

 swollen and become broadly fusiform. I have not yet succeed! 

 in observing the further development of the twin spores. 



In cultures formation of spores usually takes place wh( 

 other growth comes to an end because the substratum is i 

 longer adapted to maintain it, being either exhausted, as \ 

 are in the habit of saying, or impregnated with the produc 

 of decomposition which are unfavourable to vegetative develo; 

 ment. Formation of spores then spreads rapidly through tl 

 larger number of the cells and through the special aggregatior 

 if the particular form is present in abundance. Some of the 

 it is true do not produce spores, in some the process begii 



