34 
New comb e, Sensitive Life of Asparagus plumosus. 
toward the horizontal, and since there is no torsion of the central 
axis after displacement from its former position, it follows that 
the plagiotropic shoot is radial and not dorsiventral. Unlike most 
plagiotropic shoots, that of Asparagus does not become plagiotropic 
tili near cessation of growth. One may invert the plant at any 
time without causing the tips of main axis or branches to leave 
their horizontal position. This absence of dorsiventrality is evident 
in appearance as well as in behavior. 
In the preservation of its radial condition, Asparagus resembles 
rhizomes, 1 ) runners of Fragaria vesca 2 ) and Rubus caesius . 2 ) 
III. Effect of Light on Diageotropism. 
The matter of the participation of light in the assumption 
by aerial shoots of the plagiotropic position is not at present in 
a satisfactory condition. Thns Czapek 3 ) reports the shoot of 
Glechoma hederacea as horizontal in the dark, while both Oltmans 4 ) 
and Maige 5 ) report only the older shoots of this plant as horizontal 
in the dark, and state that the spring or young shoots grow ver- 
tically upward in the dark. Czapek 3 ) reports the shoots of 
Lysimachia numularia as vertical in, the dark, horizontal in the 
light; while Oltmans 4 ) finds these shoots vertical in dark and in 
weak light, horizontal in strong light; and Maige 5 ) finds them 
rising to the vertical position when transferred from diffussed to 
direct sunlight. Illustrations of this sort eould be multiplied. But, 
as Pfeffer 6 ) points out, these differences would in large measure 
disappear, had all authors given attention as have Oltmanns and 
Maige, to the physiological state of the material they worked 
with — had they worked with plant — members of the same 
stage of development, and had they used the same intensities of 
illumination. 
The earlier writings 7 ) on the causes of change from the or- 
thotropic to the plagiotropic position were wont to refer the be¬ 
havior to a variety of responses, differing in different plants, such 
as negative heliotropism, positive geotropism, photonasty and 
p Elfving, Über einige horizontal wachsende Rhizome. (Arbeit, bot. 
Inst. Würz. II. 489.) 
2 ) Czapek, Über die Richtungsursachen der Seitenwurzeln und einiger 
anderer plagiotroper Pflanzenteile. (Sitzber. Wien. Akad., Math.-naturw. Kl. CIV. 
Abt. I. 1895. p. 1197.) 
3 ) Czapek, 1. c. 
4 ) Oltmans, Über positiven und negativen Heliotropismus. (Flora. 83. 
1897. p. 1.) 
5 ) Maige, Recherches sur les plantes rampantes. (Ann. Sei. Nat. Ser. 8. 
VII. 1900. p. 249.) 
6 ) Pfeffer, Pflanzenphysiologie. Bd. II. 1904. p. 677. 
7 ) Frank, Die natürliche wagerechte Richtung von Pflanzenteilen. 
Leipzig 1870. — Sachs, Übor orthotrope und plagiotrope Pflanzenteile. (Ar¬ 
beit. bot. Inst. Würz. II. 1879. p. 226.) — Czapek, 1. c. 
