w. D. Mcelroy and j. w. Hastings 



163 



with NaOH, and the sokition is placed in the deep freeze. After 

 freezing and thawing, the inactive precipitate is removed by cen- 

 trifuging. Twenty-five milhhters of a calcium phosphate gel (16.7 

 mg/ml) is centrifuged, and the supernatant is discarded. The extract 

 is then thoroughly mixed with the gel and the pH adjusted to 8. 

 After 15 minutes the mixture is centrifuged and the gel is discarded. 



>- 



(9 



Z 50- 



< 



o 



a. 



CO 



500 550 600 



MILLIMICRONS 



650 



Fig. 1. The emission spectrum of the light emitted from firefly extracts (McElroy 

 and Rainwater, 1948). 



The supernatant (prep. II) is considerably more active than the crude 

 extract. Ninety milliliters of the calcium phosphate gel is centrifuged 

 and subsequently mixed with 90 ml of preparation II. The pH is 

 maintained at 8. After 15 minutes the mixture is centrifuged and the 

 supernatant is discarded. In this latter step most of the luciferase was 

 adsorbed onto the gel while the majority of the luciferin remained in 

 the supernatant. To remove the residual luciferin as well as inactive 



