Figure II~1. Attrition-type mill used to grind 

 dry materials such as fish meal samples. 



Vitamin Bj2 ^^^ assayed by a modification of the method of Hofflnan, 

 Stokstad, Hutchins, Dornbush, and Jukes (1949) • Enzymatic-digested 

 casein was omitted from the medium. The amount of glucose was doubled 

 and two grams of ascorbic acid per liter of double-strength basal 

 medium was substituted for the thioglycollic acid. The medium was 

 adjusted to pH 5*5 before autoclaving. 



The stock culture of Lactobacillus leichmannii 313 (ATCC 7830) 

 used for the vitamin B12 assay was maintained on tomato juice agar. To 

 produce the assay inoculum, the cultures were inoculated into broth 

 tubes containing single-strength medium plus 1 percent dried whey and 

 were incubated overnight at 37° C. One milliliter of this broth was 

 added to 10 milliliters of sterile saline; one drop of the suspension 

 was added to each assay tube. 



Extracts of the samples were run in duplicate at four levels for 

 each of the vitamins. Riboflavin and niacin standards were run in dupli- 

 cate at 5 levels between 0.05 and 0.08 millimicrogram; and the vitamin Bj2 

 standard at 10 levels between 0.005 and 0.8 millimicrogram (figure II-2). 



15 



