110 The Botanical Gazette. [March, 
with which they appear; but insect visits are secured by 
abundant nectar secreted by the large gynobase. The corolla 
forms a loose tube about 2™ long, beyond the tip of which 
the entire length of the conniving styles is exserted. The 
ovaries and the gynobase each occupy about half of this tube. 
The elevation of the ovaries gives them the novel function of 
obstructing the tube and to some extent concealing the nec- 
tar, and the most convenient passages to the nectar are the 
intervals between them. In the staminate flowers the gyno- 
base is developed into a more widely expanded disc, with 
lobes extending between the filaments. In this form the nec- 
tar is concealed by the filaments and by the rudimentary 
ovaries. Access to it is most convenient between the fila- 
ments. Cross-fertilization between distinct plants is secured 
by dioecism. In spite of the inconspicuousness of the flowers 
abundant insect visits are insured. 
This is a good illustration of the value of nectar as an en- 
tomophilous character of flowers. The secretion of nectar is, 
as a rule, all that is necessary to induce insect visits to 
flowers in natural situations and under fairly favorable condi- 
tions, and I am in the habit of disregarding the opinion that — 
flowers are not frequently visited by insects in all cases where A 
Tam satisfied that nectar is secreted. When nectar alone is — 
such an effective agent in securing insect visits the fact that — 
flowers display even the least advertisement in the way % 
conspicuously colored parts is conclusive proof of the extreme — 
importance of insect aid. : 
The following visitors of Xanthoxylum were taken on fouf — 
days, between Apr. 12th and rgth: j 
Sp. %, S.; (15) H. gracilis Rob. 9, s., freq.; (16) H. arcuatus 4 
Rob. 9, s.: (17) H. lerouxii Lep. 9, s.; (18) H. ligatus Say 
