No abstract

In a sense the study of the nucleolus occupies a key position in the analysis of the inter-relations of the nucleus and the cytoplasm. It is a structure within the nucleus, resembling the cytoplasmic structures in the type of nucleic acid it contains; at the same time, like other genetic effects, it is related to a definite locus in the chromosomes. Moreover, as has already been discussed in the previous paper, its function appears somehow to be connected with the synthetic activities of the cytoplasm. This being the case, the effects of genetic changes in the nucleolar regions upon the composition of the nucleolus should give some insight into the possible uses of this structure for the analysis of the problems associated with the action of the genes. Viewed from another aspect, changes in the composi- VOL. 26, 1940 515