1. The present report is the second one in a series of articles dealing with an extensive chromosome survey of the present-day chrysanthemums cultivated exclusively in Japan.
2. The cultivars of chrysanthemum used for the present study were as follows: Number of the large, medium and small flowered forms for cut flower use, including those of foreign origin, attained to 127, that of the pot-mum to 11, that of the cushionmum to 7, and that of the cooking form to 13.
3. Results of the present chromosome survey were compiled in Table 1, revealing the following facts. 1) Throughout the whole cultivars in chrysanthemums, excluding those of the exhibition use, there occurred various somatic chromosome numbers ranging 36 through 66. 2) The variation range in chromosome numbers showed definite difference from type to type of cultivars. 3) In general, the variation range in chromosome numbers was relatively slight with the large- and medium-flowered forms for cut-flower use (Japanese and foreign varieties) and also with the pot-mums (2n=53-56), forming a striking contrast to the conspicuous and remarkable complexities prevailing in their speciation procedures morphologically and ecologically. 4) In the present study, the lowest number of chromosomes, i.e., 2n=36, could be encountered for the first time with a certain small-flowered cultivar for cut-flower use. 5) The variation range in somatic chromosome numbers, i.e., 53-56, 63, 64, 66, which was obtained with the cooking varieties, was nearly the same as that in the large-flowered exhibition forms. 6) Intimate relationships of chromosome numbers to the crop season and as well to the flower colouring could not be ascertained with the large- and mediumflowered forms for cut-flower use. 7) An appreciable intimate relationship between flower size and chromosome number could be recognized only in a certain limited forms of the large-flowered chrysanthemum, such as the incurve-petaled Atsumono varieties. Most of the giant-flowered varieties were almost exclusively confined to those forms having nearly 60 chromosomes.