An account is given of an investigation, to be continued for several years, on the relationship between chitting, number of sprouts on the seed potato and the grading of the harvested potatoes. The influence of the following treatments on tuber growth (one treatment per year) was studied: (1) methods of chitting; (2) size of seed potatoes and (3) storage condition. After the first fortnight's growth, whole, sample plants were lifted weekly to study the position of stolons on the stems, and the location of the largest and smallest tubers on the plant, the size of tuber being judged by its length. At each lifting, the relative positions of the largest, the smallest and of the medium-sized tubers were the same on each plant. These positions were approximately the same in different varieties of potatoes, and the general scheme is shown diagramatically. The treatments (1), (2) and (3) showed no significant effects on formation and growth of tubers provided the sprouts of the seed potatoes were the same length. The phenomenon of secondary-tuber formation is discussed.-D.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)