Igt5| CURRENT LITERATURE 167 
It is noted that a good deal depends on the efficiency of accidental or occasional 
dispersal.—H. C. Cowes. 
The origin of Monocotyledons by self-adaptation.—A great many years ago 
HENSLOw proposed the strange theory that Monocotyledons have arisen from 
Dicotyledons through self-adaptation to an aquatic habitat. Recently he has 
published* further along similar lines; now, however, he regards the notion as 
a fact instead of a theory, although his line of reasoning is practically unaccepted 
and is quite out of harmony with the views of modern morphology and ecology. 
His argument is based on the unsound premise that such formative reactions 
as those of amphibious plants to water lie at the root of the evolutionary 
process. No one knows what lies at the root of the evolutionary process, but 
it is rather certain that it is not this. Water is regarded as causing degeneracy 
in form and structure, and aquatic seed plants are regarded as degraded land 
plants. Monocotyledons are supposed to have arisen from Dicotyledons by 
such degeneracy; non-aquatic Monocotyledons have merely crawled back 
again upon the land, though retaining their degenerate features. Other - 
authors have regarded Monocotyledons as degenerate Dicotyledons, but self- 
adaptation as a cause of degeneracy has rarely been postulated; indeed the. 
two ideas, self-adaptation and degeneracy, to the reviewer seem mutually 
contradictory. A form that is plastic and becomes suited to its environment 
should not be called degenerate, even though certain organs are pecnced or even 
lost.—H. C. Cow1es. 
Anatomy of the node.—Sr1nnottT™” has concluded that the anatomy of the 
node may be of great service in indicating the relationships of angiosperms, 
ts considers the ‘“‘trilacunar” type of node as probably the most ancient 
le type, meaning that there is a foliar supply of three bundles, each 
ae a gap of its own in the stem cylinder. This type is characteristic of 
the Amentiferae, and is present in the majority of Ranales and Rosales. 
Derived by reduction from this type, as indicated by the study of transitional 
families, is the “unilacunar”’ type, characteristic of all the Centrospermae an 
also of numerous families of the Archichlamydeae and Sympetalae. There is 
also a “multilacunar” type, derived by the ‘‘amplification” of the primitive 
trilacunar type, which reaches its highest development in Polygonales and 
Umbellales. 
In developing the facts, SInNoTT has examined about 4oo genera, distrib- 
uted among 36 orders, and gives a list of families with their number of nodal 
ad Henstow, G., The origin of Monocotyledons from Dicotyledons through self- 
adaptation to a moist or aquatic habit. Ann. Botany 25:717-744. 1911; see also 
Jour. Roy. Hort. Soc. 37:88-94, 289-294. I9II. 
#1 SINNOTT, ¥ W., Se on “ Lsensers of angiosperms. I. The 
anatomy of tk sssifi angiosperms. Amer. Jour. Bot. 
1:303-322. pls. 30-35. 1914. 
