200 



PHYSIOLOGY OF BACTERIA 



and before any appreciable amounts of fermentation 

 products have been accumulated. 



In most cases on record, no long-continued period of 

 constant growth is noticeable. From the initial lag 

 phase with its high generation time, the growthrate 



Fig. 19. — Yeast growth from different amounts of inoculum. The inoculum 

 for curve 3 was 2,095 cells, for curve 4, it was 10 times as much, for curve 5 

 10 times as much again, etc. The scale of cells per c.c. is to be multiplied for 

 curve 3 with 10', for curve 4 with 10* etc. The largest inoculum (curve 7) 

 shows the most rapid recovery from the lag period. 



gradually increases until it reaches a maximum (or the 

 generation time comes to a minimum) and then, the rate 

 does not remain there very long, but decreases quite 

 rapidly to zero. This change of rate after the maximum 

 is reached, is the cause of the point of inflexion of the 

 growth curve. 



The discussions on the cause of the ^'Endpoint of 

 Growth" (p. 231) will reveal that our knowledge of this 

 cause is still very scant. The evidence points at present 

 to some cell secretions of a specific nature as the main 



