Effect of Certain Substances on Growth and Flowering 537 



Results of observation of development of plants and also data on 

 stem growth are presented in Table 1. 



The data of the table show that all tested extracts contained GA- 

 like substances, the amount in extracts from long-day plants being 

 larger than that in short-day plant extracts, which is in agreement 

 with the results of determination of GA-like substances in maize 

 seedlings. 



The experiment shows that Rudbeckia can be made to flower 

 under short-day conditions by treating it with extracts from leaves 

 of various plants containing GA-like substances. It is especially sig- 

 nificant that flowering of a vegetating plant of the long-day type (Rud- 

 beckia) under short-day conditions could be attained by treating it 

 with an extract from the leaves of the short-day species of 'Mammoth' 

 tobacco which vegetated under long-day conditions. 



Another way of confirming our hypothesis would be to isolate 

 anthesin, which is of a nitrogenous nature, from the leaves of long- 

 day plants growing under short-day conditions, and to use it to induce 

 flowering in short-day plants growing under long-day conditions. 

 Substances of this type have not yet been isolated, but some data ob- 

 tained by us indicate to a certain extent the nature of the substances 

 which induce flowering in short-day plants located under long-day 

 conditions. 



The point here is that recently some data have been presented 

 which indicate a relation between the nature of the photoperiodic 

 reaction in plants and the peculiarities of nucleic acid metabolism 

 (6, 29), and also an inverse relationship of flowering of the short-day 

 plant cocklebur on substances of the 5-fluorouracil type, which is an 

 antinucleoside (27). Correspondingly, we undertook some experi- 

 ments to study the effect of adenine, kinetin, and some physiologi- 

 cally active substances on differentiation of flower buds of plants 

 under conditions of cultivation of isolated tips by the technique 

 proposed by Butenko (12). 



For this purpose, terminal buds 3 to 4 mm. in size were taken 

 from the main or upper lateral shoots of vegetating red Perilla plants 

 grown under long-day conditions. After sterilization the buds were 

 planted, under sterile conditions, in test tubes containing a White's 

 agar medium (31), to which were added microelements according to 

 Heller (15) and 2 per cent sucrose. 



The test tubes were then placed in a greenhouse under the follow- 

 ing illumination conditions: (1) short, 9-hr. day; (2) long natural day 

 with addition of fluorescent light to daylight; and (3) continuous 

 darkness. The experiments were carried out according to the follow- 

 ing scheme: (1) control, stock White's medium; (2) adenine (0.0001 



