A PINK YKAST CAUSTNCx SPOILAGK IN OYSTERS. 



17 



bles, and was then pressed down firmly with the points of the for- 

 ceps. This plate was incubated at room temperature with a con- 

 trol plate. 



Method 3 {Roux's physical method). — Tube cultures of liquid 

 media were prepared as usual, and some of the inoculated media was 

 aspirated into capillary pipettes. The ends of the capillary 

 pipettes were carefully sealed in the flame, and the pipettes with their 

 controls were incubated at room temperature. 



Method 4 {Buchner\s method). — Tube cultures were prepared as 

 already described. Ten cubic centimeters of " acid pyro " solution 

 were placed in a large Buchner's tube, and to this was added 1 cc. 

 of N/10 sodium hydroxid, or 2 cc. of N/20 sodium hydroxid. The 

 inoculated tube was placed inside the Buchner tube, and the mouth 

 of the tube fitted tightly with a moistened rubber stopper. The 

 tubes were incubated with controls. 



Method 5 {Wrighfs method). — After tube cultures had been pre- 

 pared as usual, the portion of the cotton-wool plug projecting above 

 the mouth of the tube was cut off with scissors, and the plug pushed 

 into the tube for a distance of 2 or 3 cm. By means of a pipette 

 about 1 cc. of 10 per cent aqueous solution of pyrogallic acid was 

 dropped onto the plug. It was absorbed immediately. By means 

 of another pipette, an equal amount of N/10 sodium hydroxid was 

 introduced, and the mouth of the tube quickly closed with a tightly 

 fitting rubber stopper. The tube was incubated at room tempera- 

 ture with a control tube. 



All these tubes were examined daily for 7 days, and the growth 

 of the yeast recorded (Table 6). 





Table 6. — Anaerobic growth of the pink yeast. 









Organism. 



Growth. 



Method. 



24 

 hours. 



48 

 hours. 



72 

 hours. 



96 

 hours. 



120 

 hours. 



144 

 hours. 



168 

 hours. 



1 



Pink veast 



+ 

 



+ 

 



+ 







+ 









 



+ 

 



+ 







+ 









 



+ 

 



+ 

 



+ 







+ 









 



+ 

 



+ 

 



+ 







+ 







+ 







-t- 

 



++ 







+ 







+ 







4- 

 



+ 

 



+4- 

 



++ 

 



++ 







+ 







4- 





Control 







2 



Pink yeast 



++ 











3 . 



Pink yeast 



++ 





Control 







4 



Pink yeast 



++ 





Control 







5 



Pink veast 



+ 





Control 







In the table a double plus sign (-] — \-) indicates a very abundant 

 growth of the yeast. It is evident that the pink yeast grows readily 

 when oxygen is excluded from the culture. The production of the 

 pigment is in no way affected by the absence of oxygen. 



