248 J- tibbs 



The most important part of this work was the determination of en- 

 zymic distribution. A suspension of perch sperm was shaken to break 

 off the tails from the heads, and the resulting suspension was sepa- 

 rated by centrifugation, as quantitatively as possible, into three frac- 

 tions — heads, tails, and final supernatant. These fractions were made 

 up to equal volumes as was an equivalent aliquot of the complete sus- 

 pension. 



Table III shows the distribution of the enzyme between the various 

 fractions, the figures relating to activity per unit volume. It will be 

 seen that the activity was concentrated in the head fraction, the con- 

 tributions by the other fractions being accountable for on the basis of 

 contamination with head material and the tendency of the enzyme to 

 be extracted into the final supernatant. 



It appears therefore that with spermatozoa possessing tails with the 

 simple and unembroidered system of (9 + 2) fibrils the acetylcholin- 

 esterase is located in the head. The apparent absence of the enzyme 

 from the other ciliates described may only mean, of course, a low level 

 of activity in these organisms. 



Histological methods for the location of the site of acetylcholin- 

 esterase activity by the electron microscope are now becoming avail- 

 able (Barrnett and Palade, 1959; Lehrer and Ornstein, 1959), and since 

 there seems to be a possibility that this enzyme may be found in the 

 mammalian sperm tail but not as a component of the inner (9 + 2) 

 system of fibrils, the application of these histological methods to this 

 type of tail may prove to be of considerable interest. 



Table III. The distribution of acetylcholinesterase in homogenates of 

 perch spermatozoa. Figures show acetylcholine chloride split in /xg/hr/ml 

 at 37° 



Specimen No. Homo ^nate Cel1 Heads CeU Tails Supernatant 



