worked their way up to the top, and you had a coating again, and 

 and you can skim them off and identify them. Now some of them 

 move up and down with the tide and others just seem to remain 

 there. So I think it is a matter of more study of the individual 

 diatoms by somebody who sits right there and watches. 



Pomeroy: I have two comments. One is on this migration matter. There 



is another paper by Callame and Debyser in Vie et Milieu in 

 which they have found that the diatoms migrate upward to the 

 surface during the low tide period on mud flats and then they be- 

 gin to migrate down about an hour before the tide gets back to 

 them and you can take a core of mud, take it to the laboratory, 

 and time it, and the diatoms will go down at the appropriate time 

 whether they are in the laboratory or out on the mud flats. 



Sprugel: Is this an effect of light intensity? 



Pomeroy: My own observations here are that you can make them go down 



by cutting the light off at any time and they will go down with a 

 speed more or less proportional to the amount of light you cut 

 off. If you partly cut it off they will go down slowly. If you put 

 them in the dark they pop right down. Now, with regard to 

 Euglena, we have Euglena here in the sediments. In the summer- 

 time we have beautiful bright green patches - Euglena blooms - 

 and I think there is no question of pollution here. These migrate 

 with amazing rapidity. In a matter of five minutes a patch will 

 flare up green and then go right out again, for reasons that no- 

 body seems to know. 



Chronic: I am interested in the quantitative amount of organic material in 



the mud. Do you have any ideas about that? Have you made any 

 measurements ? 



Moul: 



Chronic: 



No. Scher is very much interested in this thing. 1 have finally 

 gotten a physiologist interested in this sort of thing and as 1 have 

 indicated in his paper that I have read, he is taking the muds 

 back to the laboratory and has started assaying them. I was hes- 

 itant about giving this paper because I had no biochemical or 

 chemical data at all except that these indicator organisms seem 

 to indicate that there are these vitamins present or at least these 

 pseudo B-lZ's. Apparently when the salinity goes up these re- 

 quire additional amino acids, purines and pyrimidines indicating 

 that these compounds would probably be present in the mud. If 

 the organisms are going to exist at these high temperatures, 

 these things are there. 



Would you say in Barnstable mud for instance that the mud is 

 made of 20 percent organic material? 



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