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1. Some of the Floribunda roses and R. chinensis change their flower colour remarkably with the progress of anthesis. "Masquerade" and R. chinensis var. mutabilis are the typical examples. Such colour change was revealed chromatographically to be derived from the formation of the anthocyanins which have the 3-glycosidic configuration such as chrysanthemin and callistephin. These 3-monosides were scarcely detectable in flowers at their early stages of anthesis, but after full bloom a large amount of these pigments became to be recognizable. Any one example could not be met with, where such 3-monoside appearing in the flower bud stage was followed with entirely new formation of the 3:5-dimonoside towards the full blooming stage. Therefore, with regard to the glycosilation there could be noticed the existence of a law that the formation of the 3:5-dimonoside is always preceded by the formation of the 3-monoside. Moreover, if the pre-existing 3:5-dimonoside was exclusively cyanin, the 3-monoside formed after full bloom was exclusively chrysanthemin, and when pelargonin prevailed against cyanin, callistephin predominated over chrysanthemin. With the gradual change of the 3:5-dimonoside constitution from cyanin to pelargonin, the corresponding shift from chrysanthemin to callistephin was revealed. Thus, there has been established a persistent rule that the anthocyanins having the same hydroxylating pattern for B-ring show co-occurrence in this characteristic colour change. 2 Concerning the biosynthetic pathway towards the formation of the above-mentioned 3-monoside, the following two alternative possibilities have been presented. Firstly, the 3:5-dimonoside is considered to be the direct precursor of the 3-monoside and the splitting off the glucose residue at 5 position of the former becomes to form the resultant 3-monoside. Secondly, both the 3:5-dimonoside and the 3-monoside are derived from a certain common precursor, i.e., first following the same pathway to a certain stage of the biosynthetic processes, and since then diverging into the different pathways. The former scheme will due to the case, where we ought to expect the following phenomena; (i) The disappearance of the 3:5-dimonoside in roses showing the characteristic colour change with the progress of efflorescence, (ii) The accumulation of the 3 : 5-dimonoside in the ordinary roses which are lacking such a characteristic colour change, because those roses are more or less deficient in an enzymatic system which catalyze the splitting off the glucose residue at 5 position of the 3:5-dimonoside. But above these were not the cases. And moreover, this colour change is strongly affected by light intensity. The flower parts which develop the 3-monoside are confined to the parts which have received the full sunshine. The chromatograms obtained from those materials were presented elsewhere in Fig. 3, and according to the former hypothesis we can not duly explain the situation where the relative concentration of the 3:5-dimonoside stayed unchanged throughout whole the materials obtained under different environmental conditions of light. On account of the above reasons and others the latter hypothesis seems to be rather preferable. But the possibility of the linear pathway, the former hypothesis, could not be entirely excluded if we suppose the intervention of a certain colourless substance and under several additional assumptions. 3. The formation of callistephin, i.e., pelargonidin-3-monoglucoside, seems to be an enzymologically noteworthy phenomenon in connection with that of the 3-monoside. The former pigment did not occur in forms of R. chinensis which has the faculty for synthesis of 3-monoside. And in the Polyantha roses which are capable of forming a large amount of pelargonidin derivatives, the anthocyanin usually occurred in this category was confined only to pelargonin, i.e., pelargonidin-3:5-diglucoside. Callistephin occurred very rarely and even if it happened the amount was so small that it could hardly determine whether it existed originally or was derived from the partial hydrolysis of pelargonin during the preparation of sample or the executing of analysis. A large amount of this pigment was confined exclusively to the Floribunda roses. Such situations would be duly interpreted as follows; the coupling of these two enzymatic systems, one concerning with the formation of the 3-monoside and the other of the pelargonidin derivatives, will operate complementally with each other and will become to open the steady route to callistephin. This would also suggest the possibility of occasional formation of the entirely new substances under the crossings within the genetically distant forms or among the species having different enzymatic systems. 4. The situation which reveals the co-occurrence of anthocyanins having the same B-ring configuration was also made clear by T. Yoshitake (unpublished) on his studies concerning the inter-relationship between anthocyanins and fiavonols. Thus, in roses two different patterns of co-occurrence of flavonoid components, i.e., cyanin—chrysanthemin—quercetin and pelargonin—callistephin—kaempferol, were confirmed. And from the following experiments such situations were clearly proved not to be a fortuitous coincidence, but to be derived under a certain genetic background. In the crossing experiments between a Floribunda rose and several acyanic yellow varieties, i.e., between a form containing pelargonin and the forms having different flavonol constitution, the following facts were ascertained that the crosses with yellow roses of kaempferol type could entirely afford the offspring having pelargonin, while the cross with quercetin type produced almost exclusively the pelargoninfree individuals. With the shift of flavonol constitution from quercetin to kaempferol in the used paternal yellow varieties, the resultant progeny showed the corresponding shift, i.e., both the percentage occurrence of pelargonin and also its relative concentration vs. cyanin became progressively higher. And moreover, irrespective of the cross-combinations those individuals containing pelargonin were of rigid kaempferol type or nearly so, but the pelargonin-free ones were of quercetin or of intermediate type, respectively. These results suffice to show that the inferring the genetic behaviours of certain forms will be quite possible from their flavonoid constitutions and also that with the genetically very complex ornamentals such as garden roses the deliberate selection of suitable materials for the new breeding is easily practicable. 5. In the author's previous paper, the several breeding projects were presented concerning the future flower colours of garden roses. Among those practical projects the introduction of pelargonin and, moreover, the realization of co-existence of a large amount of pelargonin and carotenoid, were assumed to be one of the most fascinating and urgent projects. And in the present experiment such breeding object was more or less completely and rapidly attained, through the crosses between the yellow varieties of kaempferol type, whose flavonol constitutions are completely quercetin-free, and those of pelargonin type, which show the highest relative concentration of pelargonin as compaired with cyanin.