REVIEWS OF RECENT LITERATURE. 
GENERAL BIOLOGY. 
Role of Vexillary Organs. — To determine whether certain 
showy, so-called “vexillary” organs, external to the flower, have 
any part in attracting insects is the purpose of. a series of careful 
observations by the veteran student M. Félix Plateau." Two species 
are studied under prearranged conditions. One of them is Sa/via 
horminum, whose strict stems are crowned with showy reddish or 
violaceous bracts, occupying the upper fourth of its height, with 
the small and inconspicuous flowers arranged in verticils, with green 
bracts lower on the stem. The question was: Would these showy 
tops, often mistaken by men for flowers, deceive the insects? 
The insect visitors were mainly (more than go per cent) Hymenop- 
tera, with a few Lepidoptera and Diptera. The bees, to which fertili- 
zation is mainly due, behaved as if the showy tops did not exist, 
passing directly to the flowers, and very rarely seeming to notice the 
“ vexillary ?” parts. They behaved with the showy plants precisely as 
they did with other plants from which the showy tops had been 
removed, and just as they do with the wild germander (Teucrium), 
which has green tops. 
The number and nature of the errors committed by insect visitors 
are tabulated in detail. ‘These are mainly short haltings before the 
bracts without settling on them, and occur oftenest during passage 
from stem to stem and not on first approach. Including such slight 
mistakes, the Hymenoptera averaged but one error to fifty-five flowers 
visited ; the Lepidoptera, one error to seven flowers visited. Incase 
of the Lepidoptera (and Diptera also) the errors are oftener real 
errors, reaching even attempts at extracting nectar from the buds of 
showy bracts. These results add cumulative testimony to the acuter 
perceptions of the Hymenoptera. 
Hydrangea opuloides was also studied; both the wild form, with a 
few showy, sterile, peripheral flowers to each of its cymes, and the 
1 Plateau, Félix. Nouvelles Recherches sur les Rapports entre les Insectes et 
les Fleurs; Etude sur le Rôle de Quelques Organes Dits Vexillaires, Mém. Soc 
Zool. de France. Année 1898, pp. 339-375; 3 figs. 
736 
