296 Varietäten, Descendenz, Hybriden. — Physiologie. 
safety is the one essential: to provide it with food, and to protect it 
from the bad weather. This accomplished, the whole of the next 
growing season may well be devoted to the maturation of the embryo, 
while its germination is postponed to the third season. Hence the 
seeds of well-marked geophytes are commonly albuminous, and their 
embryos not only small, but quite undifferentiated. The geophilous 
habit is correlated with partial fusion of the two cotyledons in some 
Dicotyledons, and with a single cotyledon in others. Supposing one 
branch of Descendants from the Primitive Angiosperms to become 
geophilous, the green parts of their seedlings would inevitably be 
reduced in the early seasons of growth (Cf. Arum maculatum for an 
extreme instance of this). In the first season this reduction might 
well take the form of partial fusion of both cotyledons, leading to 
complete fusion. 
In conclusion certain objections to the geophilous origin of 
Monocotyledons are discussed. It has for instance been suggested 
that so large a dass as Monocotyledons, and one so varied in habit, 
is not likely to spring from a race of plants so highly specialized to 
peculiar conditions. It is true that the conditions of life which encou- 
rage geophilous characters are very local at the present time. Alpine 
summits are necessarily isolated: dry climates with periodic rains 
occur in limited regions scattered all over the globe. It is certainly 
difficult to conceive how a race formed in any one of these localities 
should reach the others and spread all over the globe — as Monoco¬ 
tyledons have done. But conditions may have been more favourable 
at an earlier geological epoch. Düring the glacial periods the winter 
in Europe and Northern Asia was much longer and colder than 
at present: the summer shorter and warmer. The Alpine flora of 
this continent is supposed to represent survivors of a flora which 
spread all over it during these epochs. On such a stage as this the 
great drama of the evolution of Monocotyledons might well be played 
with success. 
The geophilous habit does not, so far as the author can see, 
explain the ternate floral symmetry of Monocotyledons. Whorls of 
three and six parts are not uncommon in the flowers of the Ranales. 
It is possible that they are inherited from an ancestor which this 
alliance has in common with the Monocotyledons. A. Robertson. 
Bierberg, W., Die Bedeutung der Protoplasmarotation 
für den Stofftransport. (Flora. IC. p. 52—80. 1908.) 
Verf. kultivierte die als typische Beispiele für die Protoplasma¬ 
rotation bekannten Wasserpflanzen in der Weise, dass er sie direkt 
im Kulturgefäss unter dem Mikroskop beobachten konnte. Jede Rei¬ 
zung wurde sorgfältig vermieden. Unter diesen Umständen liess 
sich an Elodea, Hydrilla und Vallisneria niemals Protoplasmaströ¬ 
mung beobachten. Die Protoplasmarotation hat also als normale 
Erscheinung nicht die allgemeine Verbreitung, wie H. de Vries 
u. a. annehmen. 
Andererseits liess sich auf die gleiche Weise zeigen, dass 
die Strömung des Plasmas bei Chara, Nitella, Phycomyces u. a. 
einen durchaus normalen Charakter besitzt. Die Behauptung von 
Ida A. Keller, wonach die Protoplasmaströmung erst infolge patho¬ 
logischer Zustände auftreten und ein Sympton des Absterbens sein 
soll, ist somit gleichfalls hinfällig. 
Um die de Vries’sche Anschauung über die Bedeutung der 
