June, 1917] Xe?tia Following Fertilization 281 



open as usual for several hours. In from five to seven days 

 after the time that fertilization would normally have taken 

 place, the floral organs and all of the floral stem to within a 

 few millimeters of the main stem of the plant dropped off. 

 The same plant was kept growing in the greenhouse for more 

 than a year during which time no flowers whose development 

 was not interfered with in the manner so described, were 

 observed to drop off. In the Chinese hibiscus, Hibiscus rosa- 

 sinensis, a fruit that was forming apparently normally suddenly 

 dropped off. Upon examination it was found to have seeds 

 developing in only one locule, due to imperfect pollination. 

 The conclusion seems warranted that the influence from the 

 developing zygotes was not strong enough to inhibit the forma- 

 tion of the cleavage plane which cut off the stem about 1 cm. 

 below the flower. It is not to be inferred that the writer 

 believes that the developing zygote is the only influence to 

 inhibit the formation of an abscission layer or that the lack 

 of proper pollination the only cause of its appearance. The 

 question is bound up with the plant's general metabolic pro- 

 cesses, especially that of food storage. 



Hume (13) found that pollination or the lack of it brought 

 about a change in the color and texture of the fleshy material 

 of the fruit of Diospyros kaki, the Japanese persimmon. When 

 the seeds were evenly distributed the flesh was uniformly 

 dark colored, but when the seeds were not evenly distributed 

 the fruit contained both light colored astringent flesh and dark 

 colored edible flesh. "The dark flesh particularly when it 

 softens and becomes somewhat juicy, has a sort of gritty con- 

 sistency due to the presence of short well developed fibers, 

 while the light flesh lacks these and is smooth to the palate." 

 Clearly then, here is an influence due to an increasing metabolism 

 following fertilization. The effect appears in the carpellate 

 tissue outside the region of fertilization. 



Just as fertilization is not the only influence leading up to 

 cleavage plane formation, so the developing zygote is not the 

 only cause of the coagulation of the emulsion colloid with which 

 the tannin is associated, or in other words, of ripening of these 

 fruits. Lloyd (14) has observed that the entire fruit can 

 become non-astringent while still green and on the other hand 

 that some seedless fruits lost their astringency. The accumu- 

 lation of carbon dioxide in the tissues influences non-astringency 



