July 3i, 1916 



Life Cycles of the Bacteria 



689 



however, the saccharose agar was substituted by mamiite agar as pre- 

 pared for B. azotobacter. The milk organisms (No. 48 and 49) were trans- 

 planted on yeast-whey agar and into yeast-whey solution, these media 

 being the most suitable for these organisms, according to the earlier obser- 

 vations of the senior author (13). The salt-water spirilla were grown in 

 beef broth with 3 per cent of sodium chlorid. For the other organisms 

 various solutions were prepared by adding to the mineral solution as 

 used for B. azotobacter the following ingredients : 



0.1 per cent of ammonium citrate plus 0.3 per cent of glycerin for cultures 31, ^^ to 36, 



38, 40, 41, 44, and 45. 

 0.04 per cent of peptone plus 0.3 per cent of glycerin for cultures 32, 42, and 43. 

 0.02 per cent of potassium nitrate plus 1 per cent of mannite for culture 39. 

 0.04 per cent of peptone plus 0.5 per cent of lactose for cultures 48 and 49. 



All cultures were kept at 2 8° C. with the only exception of those of 

 Bad. bulgaricum (No. 49), for which a temperature of 40 to 45 ° C. is 

 more suitable. 



In the light of the results obtained by us with B. azotobacter it was not 

 difficult to find out that the life cycles of all these organisms are essen- 

 tially the same. On all good substrates they all pass quite regularly 

 through most, if not all, of the types of growth first observed with B. 

 azotobacter. In Table II the results are summarized. Type N, which we 

 have added here, represents the starlike growth previously mentioned. 



Table II. — Types of growth observed with 18 representative bacteria 

 [The laboratory numbers of the cultures are given at the head of the columns] 



The disintegration of the normal cells into the symplastic stage (D), 

 the formation as well as the further development of regenerative bodies 



