Anatomy of Teratological Seedlings . IV. 483 
shown by Chauveaud (4) for Cordyline indivisa. Moreover, the same author 
has also shown that typically the lower portion of the cotyledonary midrib, 
or the hypocotyledonary strand derived from it, is initiated as a radial file 
of xylem elements flanked by the phloem groups, this arrangement giving 
place with advancing age to two separate collateral strands, that is, to an 
Anemarrhena-like condition. Further, a number of cases are on record in 
which the earlier phases (Chauveaud’s ‘ Alterne ’ and ‘ Intermediate ’ 
groupings) do not occur in ontogeny, this being notably the case in 
Podocarpus chinensis and Ephedra distachya (16), in which the half-bundles 
are separate throughout the cotyledon and hypocotyl. Sporadic cases also 
occur in which one of the cotyledonary midribs is represented by a * double ’ 
bundle, while the other is represented by two wholly independent half- 
bundles (e. g. Echinocereus Ehrenbergii (10)). We have no information as 
to the ve^y early vascular phases of the majority of the seedlings with 
which Sargant worked, but it seems plain that the widely separated strands 
characterizing Anemarrhena may be as readily regarded as the ultimate 
derivatives of a series starting from a compact * double ’ bundle (that is, one 
consisting of a central xylem group flanked by phloems) as the initial 
member of a series which has evolved the compact ‘double’ bundle as 
a result of fusion. Which of these alternatives is the correct one cannot be 
stated with confidence, but the probabilities appear to lie with the former. 
The special type produced by the merging of the identity of the lateral 
strands in that of the main bundles does not appear to have the phyletic 
significance which Sargant would attach to it, but it serves to illustrate the 
fact that members of widely different groups (e. g. Anemarrhena , Opuntia , 
Althala, Incarvilleal) may show a common type of vascular evolution. 
De Fraine (10) further, as a result of her studies of the seedling anatomy in 
the Cactaceae, also casts doubt on the phyletic significance of the ‘ double ’ 
bundle, pointing out that this structure, in the hypocotyl, may be the 
product of widely different contributing strands. It must be borne in mind, 
however, that it is only in the more specialized cactaceous seedlings, forms 
in which the cotyledons are vestigial and in which the hypocotyl is short and 
much thickened, that the hypocotyledonary strands are produced in this 
exceptional manner, and it is very doubtful whether evidence derived from 
the study of such forms should be regarded as invalidating a view which is 
supported by the large series of facts derived from the investigation of more 
normal seedlings. 
However, while it is perhaps justifiable to say that the grounds upon 
which Sargant has based her conception of the amphisyncotylous origin of 
the Monocotyledons are open to somewhat damaging criticism, there is 
a certain amount of evidence which seems to support the view that a one- 
sided syncotyly may have given rise to a monocotylous condition. Sargant 
indeed accepts this view of the origin of the pseudo-monocotyledonous 
