w 
<- Mperlect carpels, showing that seven is evidently not the li 
1886.] Botany. 551 
observed. The relation of the horizontal axes is 0.467:1. The 
axial plane is the base, with the æ axis the negative bisectrix. 
The pleochroism is strong, a + b yellowish-gray, ¢ = grayish- 
white. a>b6>c. The analysis of Knebelite would indicate 
that it is a manganese olivine, with most of the optical properties 
of this mineral. 
BOTANY:! 
VARIATIONS OF TRADESCANTIA VIRGINICA—An interesting case 
‘of floral variation is under observation by the writer in the 
shape of a highly aberrant form of Tradescantia Ur grea, OF 
Spiderwort, also called, in quaint allusion to the ephemeral nature 
of its petals, “ widow’s tears.” Said plant presents, as the result 
of thirteen years’ cultivation, the curious aspect of a monocotyle- 
donous plant having in bloom, at the same time, flowers of dimer- 
ous, trimerous, tetramerous, pentamerous, hexamerous and hept- 
amerous types -respectively, each flower having twice as many 
stamens as sepals, petals or carpels of ovary. The plant bbe stir 
out in 1872 and received very rich treatment, so that it gave 
forth blossoms measuring two inches in diameter. In 1874 it 
to differentiate in a greater degree each succeeding year, the dif- 
ferentiated forms being typical plants and maturing seed capable 
perpetuating and possibly increasing the differentiation. The 
seed of differentiated forms gives plants having a large number of 
aberrant forms, while that of normal flowers gives a few abnormal i 
forms, showing that the plant is working out a plan of evolution. 
The Original trimerous plant was set out in 1872; in 1874 the 
7 amerous plant was evolved; in 1876 the pentamerous ; in 1879 = 
the hexamerous; in 1882 the dimerous; and in 1884 the hept- =~ 
One case a heptamerous flower had an octamerous ovary with two 
ade regarding the intensity of variation, showing that it is ver 
Pronounced, 
a ~ Roots of this plant and seeds from trimerous, tetramerous, — 
E E a , 
Edited by Professor CHARLES E. Bessey, Lincoln, Nebraska. * 
4 
