180 



LEONARD NELSON 



Fig. 6. Inorganic pyrophosphatase in frozen-dried rat sperm (a) in- 

 cubated in Na-pyrophosphate 12 min; (b) control — no substrate; (c) in- 

 cubated in Na-pyrophosphate, 30 min, after glycerination at — 20°C for 

 4 weeks; (d) control — glycerinated 4 weeks. Note that enzyme has been 

 extracted by prolonged treatment with 50% glycerol (x 15,000). 



