468 



STATE BOARD OP AGRICULTURE. 



life; and yet, in these 12 generations the bacteria had not yet recovered 

 *roin the long sojourn in the old sour milk. Then this culture was 

 transferred into gelatin, for counting. It takes about 20 generations to 

 make from one cell a colony visible to the naked eye. But most of these 

 colonies were so much smaller than those of the young, fresh cultures, 

 that we must conclude e\'en 30 generations have not been sufficient for 

 the bacteria to recover. Similar phenomena are found when bacteria 

 have been very nearly killed by poisons, and in an experiment carried 

 on by the writer six years ago where bacteria had been exposed to 1,000 

 atmospheres of pressure, the colonies grew very slowly and never even 

 approximated the size of the colonies in the control samples. 



REGENERATION OF A DEGENERATED CULTURE. 



It- seemed worth while trying to ascertain how long a time and how 

 many generations would be necessary for the old standard of growth 

 and acid production to be reached again. To this end, a series of in- 

 oculations was made from F to H, from H to 7, from I to K and from 

 K to L. In all these cultures, the number of bacteria and the acid 

 produced were determined, the results are given in Table XIII. With 

 culture H, there must have been something wrong, since the acidity 

 after the first 24 hours of growth rose so little in the following 12 

 hours. The culture L, inoculated with 0.01 cc. of the culture K, was 

 coagulated in 20 hours and had after 24 hours, the high acidity of 83°. 

 At this point, the experiment Avas discontinued under the supposition 

 that the desired point had been reached. But this was not the case, 

 for even in this last rapidly coagulating culture, the fermenting capac- 

 ity was only half of what it had been before. The reason for this 

 rapid coagulation was due to the larger number of cells per cc. The 

 rate of multiplication was soon at the former standard ,of the original 

 culture, or had even increased. 



TABLE XIII. — Regeneration of the Degenerated Strain a. 



*2S hours. 



