ADAPTATION TO PANTOTHENATE DEFICIENCY 



22-6 



207 the rate is somewhat decreased and in 107 a considerable de- 

 crease has occurred. A further decrease occurs in 57 per liter, 

 so that a continual decrease in rate of growth occurs in the 507, 

 207, 107 and 57 media, where beginning of growth is delayed more 

 and morjB as the concentration decreases, but after growth begins 

 in the 27 to 07 tubes the rate is uniform and more rapid than in the 

 57 medium. It is clear that the amount of growth when more than 

 57 of pantothenate is present bears a direct relation to the concen- 

 tration. The rates of growth in the 27, 17, 0.57 and 07 tubes are 

 very similar, but the delay before growth begins bears a close re- 

 lation to the concentration of pantothenate. 



CUITUIC u n 



/v -^^^': y 



Fig. 22-1 The Growth ol Cultures Nos . 1 (S. Cerevisiae, 

 Diploid), 2 (S. Carlsbergensis , Diploid), 7 (S. Car Isbergens is , 

 Haploid, CIA) and 10 (S. Carlsbergensis x S. Cerevisiae, Diploid 

 Hybrid) in Burkholder's Medium Containing Different Concentra- 

 tions of pantothenate. The solid lines represent tlie original 

 inoculations; the dotted lines represent transfers from these 

 inoculations as indicated, 100-0 being a transfer from 1007 to 

 07. 



When transfers from the culture tubes without added pantothenate 

 were made to similar tubes likewise without added pantothenate (0-0) 

 growth occurred about 150 hours sooner in the second than in the 

 original test. These curves of growth are shown as dotted lines on 

 the graph. As the yeast was transferred serially in medium, the 

 delay before growth started was further shortened. The fifth trans- 

 fer (0-0-0-0-0) began to grow sooner in the medium without added 



