Abstract
The proportion of ribo-somes present as polyribosomes rapidly increases from about 10% in fresh discs of carrot root to a constant value of about 65% during aging of discs. The results based on the effects of actinomycin D and 5 -fluorouracil indicate that the synthesis of a fraction of RNA having the properties of messenger RNA is required for this tansition. The rapid increase in polyribosomes is one of the earliest biochemical changes observed during aging of storage-tissue discs.