A PINK YEAST CAUSING SPOILAGE IN OYSTERS. 



19 



Each portion of the different media was titrated after sterilization, 

 and the titre recorded. The tubes were then inoculated with the 

 pink yeast, incubated at room temperature with control tubes of 

 the same reaction, and examined for 7 days. The growth in each 

 tube was recorded. 



Table 8. — Relation of (/rowth of the pink yeast to reaction of the medium. 



Reaction. 



Growth. 



Before 

 steriliza- 

 tion. 



After 

 steriliza- 

 tion. 



2t hours. 



48 hours. 



72 hours. 



9G hours. 



120 

 hours. 



144 

 hours. 



108 

 hours. 



- 1 



- O.S 



+ 



+ 



+ 



+ 



+ + 



+ + + 



+ + + 



Neutral. 



4- 0.3 



+ 



+ + 



+ + + 



+ + + 



++ + + 



+ + + + 



+ + + + 



+ 1 



-f 1.0 



+ 



+ 



+ + 



+ + + 



++ + 



++ + + 



+ +++ 



+ 2 



-h 2.0 



+ 



+ 



+ + 



+ + 



+++ 



+ + + 



+++ + 



+ 3 



-f 2.8 



+ 



+ 



+ + 



+ + + 



+ + + 



+ + + + 



++ + + 



+ 4 



+ 3.9 



+ 



+ 



+ 



+ 



+ 



+ 



+ 



+ s 



-f 4.8 



+ 



+ 



+ 



+ 



+ 



+ 



+ 



+ 6 



-i- 5.6 



+ 



+ 



+ 



4- 



+ 



+ 



+ 



+ 7 



+ 7.0 



+ 



+ 



+ 



+ 



+ 



+ 



+ 



+ 8 



+ 7.7 



+ 



+ 



+ 



+ 



+ 



+ 



+ 



+ 9 



+ 9.2 



-f 



-j- 



+ 



-1- 



4- 



+ 



4- 



+ 10 



+ 10.5 











+ 



+ 



+ 



+ 



"^ 



The terms used in describing the growth in Table 8, which are 

 comparative only, are as follows: Very slight to slight ( + ) ; fair 

 to very fair (-| — [-) ; good to A'Cry good (-| — | — [-) ; excellent to heavy 

 (-| — I — I — [-). No growth appeared in any of the control tubes. Nor 

 did growth occur in any medium the reaction of which was less 

 than — 0.8. The growth in the acid media was very slight in the 

 cultures which contained acid to a greater extent than 2.8 per cent. 

 The best growth was obtained in media the reaction of which was 

 between -\-0.?> and +2. In the cultures the reaction of which was 

 +10.5 the growth was barely discernible, and this may be taken, 

 as the limit of acidity. 



RESISTANCE TO DESICCATION. 



Yeasts, in general, are very resistant to drying, and this has been 

 found to be the case with the pink yeast. Pasteur (1879) studied 

 a yeast which continued to grow after being dried for 1 year. 



The pink yeast was dried on glass rods in a specially constructed 

 drjdng-box. This consisted of a wooden box, the cover of which 

 was perforated. Each one of the holes in the cover of the box was 

 plugged with cotton, and the whole apparatus was sterilized in the 

 autoclave at 15 pounds for 15 minutes. Corks which would fit the 

 holes in the cover of the box were selected, and small glass rods were 

 inserted in the corks. These were sterilized in the autoclave also. 

 Forty-eight-hour-old cultures of the pink yeast were made in dex- 

 trose broth. The sterile rods were dipped in these cultures, and the 

 rods, with some of the culture adhering to them, were suspended in 

 the sterilized box. Each day one of the rods was removed from 



