1897.] NATURAL SCIENCES OF PHILADELPHIA. 179 



believe growth is modified by temperature it may be noted that it 

 was cool for the season — 65° F. There was absolutely no growth in 

 the corolla until 9 A. M. Up to this time the corolla was enjoying a 

 rest, but then the lobes began to unfold, occupying about two hours 

 to reach their normal salver shape form. By opening the flowers 

 at various times before 9 A. M. we note that the authers are not at 

 rest ; they are regularly increasing in size. By 9 A. M. they have 

 reached their full development, and the cells burst and discharge 

 the pollen simultaneously with the unfolding of the corolla lobes. 

 By now opening a flower-bud that is a day behind this one in devel- 

 opment, we note that while the corolla with its attached stamens 

 was growing, the style was at rest. It evidently starts on its new 

 rhythm of growth the evening before the full. opening of the corolla, 

 that is to say when the ultimate length of the latter has been reached, 

 the style starts on its advance. It does not quite reach its ultimate 

 length when tbe anther cells discharge their pollen, but the appressed 

 stigmas receive and retain the scattered pollen grains. Returning 

 now to the corolla, we find that after full expansion, at about 11 A. 

 M., it continues without change the whole of the next day, wither- 

 ing and falling away on the third. It" may be noted, however, that 

 a very light touch causes disarticulation the second day, showing 

 that fertilization has already been accomplished. The lobes of the 

 pistil do not diverge until the second day, but it is evident that fer- 

 tilization is not dependent on the expansion of the lobes. The pol- 

 len tubes act in advance of the expansion of the lobes. 



That the morning was rather cool for the season may have been a 

 reason why no insects visited the flowers till noon. Humble bees 

 were the first in the field, rifling the sweets by cutting the tubes of 

 the corolla. The honey bee soon followed, using the slits made by 

 the humble bees, and during the afternoon several species of lepidop- 

 tera gathered the nectar by the legitimate entrance. 



The nectar is secreted by the " hypogynous disk." It is remark- 

 able, however, that I could find no exudation on the first day of 

 opening. The flow seems to commence on the second day, and is 

 most abundant when the flower is about to wither and long after 

 the fertilization of the flower has been effected. I have already 

 placed this fact on record in connection with Lonicera and some 

 other flowers. It is probably a general fact, strangely overlooked 

 in treatises showing the relation of the honeyed secretions to the 

 agency of insects in the cross-fertilization of flowers. So far as the 



