92 The Biochemistry of Semen 



carbon monoxide, as if they were in the dark. Under these condi- 

 tions, he found that carbon monoxide depressed the respiration 

 without a corresponding decrease in sperm motiUty. A similar con- 

 clusion that respiration can be dissociated from motility was reached 

 by Robbie (1948) from his study of the effect of cyanide on the 

 spermatozoa of the sand-dollar {Echinarachnius par ma). 



The cytochrome system of sea-urchin spermatozoa includes cyto- 

 chrome e and in this respect, it differs from mammalian sperm 

 (Keilin and Hartree, 1949). Starfish {Asterias forbesii) spermatozoa 

 on the other hand, exhibit a spectroscopic pattern of cytochrome 

 very similar to sea-urchins (Borei and Metz, 1951). There is also 

 some evidence that cytochrome occurs in plant sperm. This follows 

 from the observation by Rothschild (1951c) that the movements of 

 bracken spermatozoids {Pteridium aquilinum (L.) Kuhn) are photo- 

 reversibly inhibited by carbon monoxide. 



The information gained by Zittle and Zitin (1942a) from experi- 

 ments on the oxidation of /7-phenylenediamine by spermatozoa 

 disintegrated by sonic treatment, coupled with earlier observations 

 on the indophenol colour reaction, indicated that the cytochrome 

 system is located in the cytoplasm of the middle-piece and tail, 

 rather than in the sperm-head. Our own spectroscopic studies led us 

 to the same conclusion; the examination of the disintegrated middle- 

 pieces and tails revealed the presence of all three cytochromes with 

 cytochrome a predominating; these 'homogenates' oxidized rapidly 

 both /7-phenylenediamine and succinic acid, and the rate of oxygen 

 consumption could be substantially increased by the addition of 

 cytochrome c. 



Catalase 



It did not escape Miescher's notice that salmon spermatozoa differ 

 from other cells by their restricted ability to decompose hydrogen per- 

 oxide. Some slight catalase activity has been reported in mammaUan 

 semen (Shergin, 1940) but it is questionable whether this was due 

 to the spermatozoa themselves or to some accidental contamination 

 of semen with blood, pus or bacteria. The deficiency of catalase in 

 normal and cleanly collected bull semen is in fact, so typical that 

 Blom and Christensen (1944, 1947) base on it a method for rating 

 the 'hygienic quality' of bull semen; the test is carried out in Denmark 



