A study of floral differentiation has been made upon 13 vars. of soybeans grown on 9 photoperiods, including continuous light. The vars. Agate, Mandell, Hudson Manchu, Minsoy, Mc Crostie''s Mandarin, Wisconsin Early Black, Batorawka, and Mandarin initiated flower primordia on all photoperiodic treatments employed. These vars. normaly mature seed in 105 days or less under field conditions. No plants of the vars. Biloxi, Avoyelles, Otootan, and Peking, and few of Tokyo, initiated flower primordia on photoperiods longer than 16 hrs. These vars. require 125-175 days to mature seed in the field. The initiation of flower primordia in many vars. under continuous light shows that darkness is not a necessary condition for floral initiation in them. In Agate, one of the vars. that initiates flower buds most readily on continuous light, the reactions causing induction are accelerated if the plants are subjected to daily periods of darkness. Although these reactions take place in continuous light they proceed more rapidly if there is a daily alternation of light and dark. Chemical analysis of the vars. Biloxi and Agate were made at the ages of 2, 3, 4, 5, and 6 weeks. In general Agate contained less total and less soluble forms of N and more carbohydrates than Biloxi. The starch content of Agate reached a max. at 3 weeks and declined progressively with age; in Biloxi the trend of the data indicated that a maximum had not been reached during the expt. The maximum carbohydrate content in Agate occurred at the time floral initiation was beginning.