IgIo0] CURRENT LITERATURE 239 
communication to the Amsterdam Academy.?4 Miss PEKELHARING found it 
possible, by using potash-alum properly balanced in the culture solution, to grow 
some roots of Lepidium sativum fairly straight and free of starch grains. Never- 
theless, these roots, in many cases, showed geotropic curvatures; from which it is 
evident that there is perception independent of statolith starch, however useful 
this may be when present.—C. R. B 
hromosomes of Taraxacum and Rosa.—In 1903 RAUNKIAER found that 
Taraxacum developed embryos even when all the anthers had been removed, and 
a subsequent cytological study by MurBecK and Jurt showed that the embryos 
developed from the egg without fertilization. A recent study by ROSENBERG?S 
shows that in the form called Taraxacum conjertum a typical tetrad of megaspores 
is formed from the megaspore mother cell, and that the reduced number of chro- 
mosomes is 8, which can be counted in an early stage as prochromosomes. JUEL 
had reported 12 or 13 as the reduced number and 26 as the diploid number in 
apogamous forms of Taraxacum. 
In several forms of Rosa it has been known that embryos develop even when 
the anthers have been removed, but RosENBERG is not yet able to say upon cyto- 
logical evidence whether these forms are apogamous ornot. In the pollen mother 
cells of Rosa canina he finds, usually, about 20 univalent chromosomes and 7 
bivalent ones. - During the first mitosis chromosomes become disarranged, as _ 
in Hemerocallis, and more than four pollen grai fi from a singl ther 
cell. He thinks that the suggestion may not be entirely unfounded that the univ- 
alent chromosomes, which normally split at the second mitosis, may split at the 
first, and thus show a transition to the vegetative mode of division. He gives a 
table showing the relatively high chromosome numbers of apogamous forms.— 
CHARLES J. CHAMBERLAIN 
Light and germination. HEINRICHER”® finds, in agreement with REMER, 
that the seeds of Phacelia tanacetifolia are greatly hindered in their germination 
by light. Seeds just harvested and not first dried out will not germinate at all 
in white light, nor in the less refrangible rays, while a considerable percentage 
Serminate in darkness and a smaller percentage in the more refrangible rays. 
A period of drying, whether it occurs in darkness or light, greatly increases 
8ermination in darkness and in the more refrangible rays, while it leads to a low 
percentage of germination in white light and in the less refrangible rays. The 
behavior of these seeds toward light is in most respects just opposite to that of the 
seeds of Veronica peregrina. 
ser 
* Went, F. A. F. C., The inadmissibility of the statolith theory of geotropism. 
Proc. Koni kl. Akad. Wetens. Amsterdam 1909: 343-345. 
SENBERG, O., Ueber die Chromosomenzahlen bei Taraxacum und Rosa. 
Svensk. Bot. Tidskrift 3:150-162. figs. 7. 1909. 
2° HEINRICHER, E., Keimung von Phacelia tanacetijolia Benth. und das Licht. 
Bot. Zeit. 671:45-66. 1909. 
