192 PROCEEDINGS OF THE ACADEMY OF [1883. 



which about this time fills the canal of the micropyle, but after- 

 wards dries up, and thus draws the captured pollen-grains to the 

 nucleus, where they immediately emit their pollen-tubes into the 

 spongy tissue. In Gupressinese^ Taxinese and Podocaryese this 

 contrivance is sufticient, since the m3'crop3'les project outwardly; 

 in the Abietinese^ yvhere they are more concealed among the scales 

 and bracts, these themselves form, at the time of pollination, 

 canals and channels for this purpose, through which the pollen- 

 grains arrive at the micropj-les filled with fluid " (Strasberger).^ 

 Mr. Meehan said that in his former observations on liquid exuda- 

 tions in Thuja and other plants he was inclined to adopt the 

 suggestion of Sach as to the purpose of the liquid suppl}^ ; but as 

 it was here in Abies so long after fertilization must have taken 

 place, and as it was held up in the deep recesses of the scales of 

 the pendent cone, where it could hardly be possible the wind could 

 draw up the pollen ; and as, moreover, the extract shows that these 

 eminent botanists believe Abietineae does not need the moisture 

 they did not know existed in this abundance, we must look for 

 other reasons, which, however, do not yet seem to be apparent. 



September 11. 



Mr. Meehan, Yice-President, in the chair. 



Sixteen persons present. 



The death of the Curator-in-charge, Charles F. Parker, on the 

 7th inst., was announced. 



Irritability in the Flowers of Centaureas and Thistles. — Mr. 

 Thomas Meehan called attention to some flowers of various com- 

 positse on the table, sent by Miss Mary E. Powel, of Newport, 

 Rhode Island, who has observed a singular motion in the florets 

 of Centaurea Americana. This motion had long been known 

 to German botanists, and a reference to some features of it 

 may be found in Sach's Text-book of Botan}^, and there was an 

 illustrated paper by Cohn in Zeitschrift fur ivis. Zoologie^ vol. 

 xii, showing the mechanism of the contraction of the anthers. 

 As, however, the motion had failed to attract the attention of 

 American observers, or at least he knew of no refei'cnce to it in any 

 American work at his command, he believed it might do good 

 service to place on record an independent statement of the phe- 

 nomena as exhibited by the specimens before us. 



Besides the motion in Centaurea ^?7jeWcana, observed b}^ Miss 

 Powel, Mr. Meehan said that he found a similar motion in the 

 following plants growing in his garden : Centaurea alba, Centaurea 



' Sach, Text-book of Botany, Oxford edition, p. 449. The various ways 

 of spelling micropyle in the same paragraph, are of course retained in the 

 quotation. 



