66 BOTANICAL GAZETTE | JANUA 
opposed to Hanstein’s. The suspensor cell enlarges considerably, but _ 
remains undivided, and all the embryo and the secondary suspensor cells 
are derived from the embryo cell which first becomes divided transversely 
into a number of segments. In V. fexz/is the terminal segment of the 
row thus formed gives rise to the cotyledon, the second to the stem, and 
the third and fourth to the root. In Zannichellia the terminal segment : 
divides vertically, one-half becoming converted into the cotyledon, and the — 
other into the stem, the second, third and fourth segments give rise to. 
root, and the fifth to the root-cap. The embryo of WV. fe-rilis is peculiar 
having no trace whatever of a root-cap; that of Zannichellia in the terminal 
origin of the stem. 
The endosperm in both genera is rudimentary. In the later stages of 
embryo-sac of V. flexi/is there is always present near the antipodal cell 
large nucleus which increases to an enormous size but does not und 
division. Since Professor Campbell did not succeed in demonstrating 
fusion of the polar nuclei, he is inclined to doubt whether such a fusion takes 
place, and to regard this large persistent nucleus as one of the unfused 
nuclei. As an alternative explanation he suggests the possibility that this 
although fusion of the polar nuclei probably occurs, as well as by Schaffner 
observation? that in Sagitlaria variabilis there are only two or three der! fi 
tives of the lower endosperm. nucleus and these enlarge enormousl 
W.R ‘ 
ITEMS OF INTEREST on the” subject of insect pollination are given 
E. Ule® Observations, made chiefly in Brazil, indicate that Asclepias C™ 
Ssavica is usually pollinated by Danais Euripus, ‘a large red-brown § 
butterfly,” whose wings resemble in color the flower of the Asclepias. 
said that this butterfly rarely visits other flowers, though large num ) 
nectar-bearing flowers are often found in the same locality. Other bu 
frequently seen in this locality very rarely visit this particular species 
when visiting it were seen to load themselves with pollen just as the 
Bun tus, and probably bring about pollination with equal effectiveness | 
ima smaller number of cases. It is also said that this butterfly has 
The caterpillars of the butterfly live and feed upon the plan 
seldom cause any injury to it. 
The author cites the above as a case of symbiosis, under the cates 
mutualism. The Asclepias is pollinated and pays for the favor i 
7 Bor. Gaz. 23: 26 | 
ae 7267. 1897. 
Ber. der deutsch. bot. Gesellschaft 15 3 385-387. 1897. 
