350 H. H. R()Bp:rts, r. .t. hhittkx, and b. j. mccarthv 



force may exi.<t. Soon thereafter the cosomes are (lish)(l<2;e(l. j)erhaj)s l)y 

 accumulation of piotein, and can he t'ound associaterl with ribosomes. 

 Such a transfer would seem moi'e phiusihle if tlic recijiient I'ibosome were 

 equally extended. 



At present there are no certain facts relating to the state of organiza- 

 tion of nucleic acids in the living bacterial cell. A model showing the 

 DNA, the eosomes, neosomes, and I'ibosomes extended as roughly parallel 

 strands seems equally valid or e\-en jireferablc to a model in which the 

 DNA is packed in a nucleus surrounded by a multitude of small round 

 ribosomes. 



X. Epilogue 



In this review of ribosome synthesis we have attempted to fractionate 

 the material and to present the facts in Sections I-VIII partially sepa- 

 rated from the interpretations of Section IX. In so doing we have tried 

 to show that many of the currently popular hypotheses are quite ac- 

 ceptable and not in conflict Avith the facts. They should not, however, 

 be considered as proved until other alternative interpretations have been 

 ruled out. In addition, we have attempted to point out the areas where 

 additional experiments are most needed. We hope that we may have 

 encouraged some of our readers to measure the number of enzyme- 

 fonning units, to devise an assay for template RNA, or to carry out a 

 cell-free synthesis of ribosomes. 



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