TEXT-BOOK OF BACTERIOLOGY. 13 



the temperature of the incubator (35-37 C.), which seems espe- 

 cially suitable. With insufficient oxygen the anthrax bacilli also 

 produce no spores, and this is so noticeable that in the upper strata 

 of fluids in which they sink to the bottom and cannot regain the 

 surface on account of their immobility, the spore-formation is 

 greatly retarded, and within the body of a dead or living animal it 

 entirely ceases. 



On the other hand, by measures which in some way or other act 

 prejudicially on the bacterial protoplasm, we can artificially rob it 

 temporarily, or permanently, of its capacity for spore-formation. 



K. B. Lehmann and Behring discovered the "non-spore-produc- 

 ing " anthrax, which cannot, under any circumstances, be brought 

 back to spore-production. 



Sporulation is, in many respects, a remarkable phenomenon. I 

 have stated that it has been proposed as a basis for a scientific ar- 

 rangement of the bacteria. 



Besides the manner of sporulation above described, in which the 

 spore develops in the interior of the fruit-bearing cell as a special 

 formation, observers have believed there was another way in which 

 such reproductive organs originated. 



It has been found that whole cells separate from their connec- 

 tion and form the beginning of new groups. No very striking- 

 change of form takes place in these cells; they only appear to in- 

 crease somewhat in size and refractive power, and also possess a 

 firmer, darker envelope. 



This kind of sporulation, in which the entire cells are said to 

 undertake the functions of permanent cells, has been designated as 

 arthrosporic, in contra-distinction to the ordinary endosporic fruc- 

 tification, where special new-formed organs arise in the interior of 

 vegetative cells. From this difference the criteria for a classifica- 

 tion have been derived. 



As already stated, observations are neither numerous nor cer- 

 tain enough for us at the present time to found upon them the 

 principle of a finally correct classification. When such an experi- 

 enced man as Prazmowski recently expressed doubts as to the ex- 

 istence of an arthrosporic sporulation in the bacteria in general, 

 and even in the micrococci (in which it was thought to have been 

 most clearly seen), and when he regards endogenic spores as the 

 only possible ones, it is best to proceed cautiously. 



From a biological point of view sporulation is also important, 

 since the spore as a " persistent form " can do much more for the 

 preservation of the species than the transitory "growth forms" 

 of bacteria. 



