176 General Notes. [ March, 
dioxide in chlorophyll are untrustworthy. Such experiments should be 
made upon plants which have no starch already stored up, or upon de- 
tached leaves which contain no starch. 
Tue Errect or Frost on CHLOROPHYLL-GRANULES. — Hab- 
erlandt states that the granules except in evergreens undergo changes 
at 4° to 6° C. The granules thus affected contain cavities (vacuoles), 
become rent on the outside, and aggregate into larger or smaller masses. 
The granules which contain starch are more easily destroyed by frost 
than those which contain none. ‘The chlorophyll in the palisade tissue 
(the denser parenchyma) is more easily injured than that in the spongy 
tissue, and the latter than that in the guardian cells of the stomata. 
DicnoGamy or Acave. — The flowering of a plant of Agave yucce- 
folia Red. (Bot. Mag. t. 3213), in a private collection near Boston, has 
given abundant opportunity to watch the development of its flowers, and 
to confirm in regard to this species Engelmann’s statement (Notes on 
Agave. Transactions of the Academy of St. Louis, vol. 3, December, 
` 1875), that the flowers of this genus are “ vespertine or nocturnal, and 
proteranderous.” 
Agave yuccefolia must be referred to Engelmann’s second section, 
Getminiflore, although on our plant the lower flowers alone are borne 
in pairs. The forty uppermost flowers of the spike spring singly each 
from the axis of a bract, and in this approach his first section, Singuli- 
flore. The production-of solitary flowers on the upper portion of the 
spike is possibly abnormal ; but should this prove a constant character a 
slight modification of Engelmann’s sections of the genus will become nec- 
essary. In the figure in the Botanical Magazine the arrangement of the 
flowers is not distinct; but in the accompanying description we read, 
“ Flowers often two together.” 
The scape first made its appearance on November Ist, and continued 
to grow until January 6th, when it had attained a height of ten feet, the 
first flowers opening about five P.M. on that day. Shortly after the 
opening of the flower the filaments attain their full development, and 
are exserted 9!’ beyond the lobes of the perigone. The style at this 
time is barely exserted and much reflexed, the stigma bearing these pap- 
illose lines radiating from its centre down the middle of each of the three 
bes. A little before eight o’clock on the morning after the opening of 
the flower, the tube of the perigone is entirely filled with the honeyed sè- 
cretion, which is slightly odoriferous, sapid, straw-colored, and very 
abundant. At ten P. M. of the second day, or seventeen hours after the 
opening of the flower, the anthers burst. At this time the style bee 
elongated and partially straightened until the stigma, over which the 
‘papillae have not as yet extended, is placed just above the introrse ~ ae 
thers, and in such a position that none of the pollen discharged from 
them can reach its surface. During the third day the style continues tO 
elongate and straighten. On the morning of the fourth day the style 18 
