POLYNUCLEOTIDE SYNTHESIS IN NUCLEOLUS AND CHROMOSOMES 1 85 



15. 'rAVLOR, J. H. .'tni. J. Hot. 45: 123, 1958. 



16. Taylor, J. H. .Ini. /. Bot. In press. 



17. Taylor, J. H., R. D. McMaster and M. F. Caluya. Exper. Cell Res. 9: 460, 1955. 

 iS. Taylok, J. H., P. S. Woods and W. L. Huchrs. Proc. Nut. .had. Sd. 43: 122, 1957. 



19. \'iNcENT, W. ,S. Science 126: 306, 1957. 



20. Vincent, W. S. In: Beginnings of Etnhryonic Devclopnicnt, edited by C. Metz, A. Tyler 

 and R. C. von Borstel. Washington, D. C: Am. A. .Adv. Sci., 1957. 



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DISCUSSION 



W . S. Vincent, J. H. Taylor 



J)r. Vincent: In the starfish nucleolus soluble nucleotides appear to be produced in 

 the nucleolus. Can you detect these, as a possible precursor of cytoplasmic RNA, by your 

 procedures.? 



Dr. Taylor: One of the limitations of the autoradiographic method is the difficulty 

 of working with water-soluble substances. The film cannot be properly placed on the 

 slides unless it is wet and, therefore, difl^usion of water soluble substances occurs. There 

 is also the original problem of retaining such substances lu situ during the dehydration 

 and fixation of the tissues. Methods for precipitation of nucleotides as salts of heavy 

 metals ha\e been utilized to some extent by others, but we have made no attempt to 

 study the substances removed from the tissue by hot 70 per cent ethanol and cold 

 trichloroacetic acid. 



