SPORE FORMATION 7 



of speculation. Furthermore, in the case of bacteria preferring 

 the presence of oxygen for their growth, an abundant supply 

 of this gas may favour sporulation. It is probable that even 

 among bacteria preferring the absence of oxygen for vegetative 

 growth, the presence of this gas favours sporulation. Some 

 facts relating to the cases in which two spores are formed in 

 one bacterium have been adduced to support the view that 

 sporulation may represent a degenerate sexual process. Here a 

 partial fission of a cell has been observed, followed by a re- 

 fusion of the protoplasmic moieties and the formation of a spore 

 at each end of the rod. The second view with regard to 

 sporulation is that a bacterium only forms a spore when its 

 surroundings, especially its food supply, become unfavourable 

 for vegetable growth ; it then remains in this condition until it 

 is placed in more suitable surroundings. Such an occurrence 

 would be analogous to what takes place under similar conditions 

 in many of the protozoa. Often sporulation can be prevented 

 from taking place for an indefinite time if a bacterium is 

 constantly supplied with fresh food (the other conditions of life 

 being equal). The presence of substances excreted by the 

 bacteria themselves plays, however, a more important part in 

 making the surroundings unfavourable than the mere exhaustion 

 of the food supply. A living spore will always develop into a 

 vegetative form if placed in a fresh food supply. With regard to 

 the rapid formation of spores when the conditions are favourable 

 for vegetative growth, it must be borne in mind that in such 

 circumstances the conditions may really very quickly become 

 unfavourable for a continuance of growth, since not only will the 

 food supply around the growing bacteria be rapidly exhausted, 

 but the excretion of effete and inimical matters will be all the 

 more rapid. 



We must note that the usually applied tests of a body 

 developed within a bacterium being a spore are (1) its staining 

 reaction, namely, resistance to ordinary staining fluids, but 

 capacity of being stained by the special methods devised for 

 the purpose (vide p. 110); (2) the fact that the bacterium 

 containing the spore has higher powers of resistance against 

 inimical conditions than a vegetative form. It is important to 

 bear these tests in mind, as, in some of the smaller bacteria 

 especially, it is very difficult to say whether they spore or not. 

 There may appear in such organisms small unstained spots, the 

 significance of which is very difficult to determine. 



The Question of Arthrosporous Bacteria. It is stated by Hueppe that 

 among certain organisms, e.g., some streptococci, certain individuals may, 



