102 PIERRE H. GONSE 



given by Chance (1954a, 1957) and Chance and Williams (1955), 

 namely, 16, 19, and 22 for the alpha absorption bands of cyto- 

 chromes a, c, or c x , and b, respectively. The coefficient 22 was also 

 considered valid for the fr-like cytochromes of Spisula. A coefficient 

 of 1 1 at the trough of reduced flavoproteins at 460 m^, of 6 for py- 

 ridine nucleotides at 340 m^t, and of 91 for cytochrome a 3 at the 

 Soret absorption band were also adopted. 



Presentation of Results 



The experimental procedure to be followed in recording a series 

 of difference spectra on a single preparation has been described by 

 Chance (1954b). Briefly, an experiment at room temperature begins 

 with a pair of cuvettes (2 ml) filled with the same suspension which, 

 on recording, yields a flat base line. Modification of conditions al- 

 ternatively in each cuvette gives, step by step, difference spectra and 

 base lines. Spectra are described here (e.g., Fig. 1) by giving, inside 

 the first parentheses the successive treatments performed on the more 

 reduced sample, followed by a minus sign and a second parenthesis 

 summarizing successive conditions performed on the more oxidized 

 sample. 



Abbreviations used in the text and figures are: RP for Ringer 

 phosphate medium, GG for glycylglycine, SW for sea water, PN for 

 pyridine nucleotides, FP for flavoproteins, DNP for 2,4-dinitro- 

 phenol, and TN for turnover number. The notation Z , 2 designates 

 oxygen consumption of 10 s spermatozoa expressed in microliters of 

 2 per hour. 



Identification of Respiratory Enzymes. 



A rather complete picture of the metabolically reducible respira- 

 tory pigments is obtained from a recording of the spectroscopic dif- 

 ference between the washed starved aerobic sperm sample and the 

 anaerobically reduced one. The starved sample of bull spermatozoa 

 (Fig. 1) has a low respiration on the order of 0.01 [xM (X/sec (Z 0o of 

 about 1) and remains aerobic for the duration of the experiments, 

 whereas in the other sample, addition of 20 mM lactate evokes a ten- 

 fold increase of respiration and exhaustion of oxygen in 5 minutes. 



