998 General Notes. [ December, 
insect passes from one nectary to the other, its bill is likely to 
carry pollen to the stigma. 
As in other cases of dimorphism, all flowers on the same root 
have the same form. Much care should be taken in verifying 
this statement, for, as in both forms the pistil soon elongates, 
after the flower has passed its prime, it is easy to mistake older 
flowers of the short-styled form for long-styled ones. But com- 
paring flowers which have just opened, or before they have been 
fertilized, the facts stated above will be clearly seen. The styles 
in the two forms differ in length a little less than one millimetre. 
The dimorphism in this case seems to be imperfect. There 
are two lengths of stamens, and two lengths of pistils to corre- 
spond, but while the different pistils are distributed to different 
plants just as in Houstonia, Lithospermum, etc., the different 
stamens are not even distributed to different flowers, Moreover, 
the longer stamens are twice as numerous as the shorter. These 
facts suggest the following queries: . 
1. May we not have in this case two plans for cross-fertiliza- 
tion coéxisting, viz., one more or less analogous to other cases of 
heterostylism, and the other like that in the Rosacee, etc., where 
stamens and pistils are equally prominent, to profit by the hap- 
hazard movements of insects visiting the flowers ? 
2. Do similar relations exist, in all the Cruciferae, or are these 
variations which indicate a transition stage in the development of 
dimorphism ? 
To direct observation and obtain an answer, especially to the 
latter question, has been one purpose in publishing the facts given 
above.— ¥. E. Todd, Tabor, lowa., 
Motion oF THE Fruit oF TILIA WHILE IN THE Air.—Every 
one is familiar with the singular inflorescence of the genus Tilia, 
in which the long peduncle, really axillary to the large papery 
bract, is so adnate to this for about half its length, as to appear to 
spring from its middle, Well known as are these lindens oF 
limes, and especially the Zilia Europea, I do not recall having 
seen any mention of the use that the plant makes of this scale in 
distributing its fruit. As the globular nuts ripen, the scale be- 
comes more dry and papery. Italso bends back upon itself from 
the point where the peduncle becomes free. It is weighted, as 
it were, by the fruit balls below. Sometimes moreover, there 1S 
a lateral twist to the wing, making it not unlike the fluke of a 
propeller. Now, when a breeze disengages this apparatus, it falls 
by its own weight, but, through the influence of the wing, at once 
begins to revolve rapidly upon its axis, looking like the governot 
_ ofa steam-engine in rapid motion. I take it there is here a¢ a 
_ for mathematical research, but that is unfortunately out of BY 
- . 
i line. Will not some botanist of a mechanical turn, if such a be- 
ing exists, study into this matter a little? I take it that the pt : 
of the apparatus is, as in the case of the ash, to propel "© 
