66 Sargant . — Theory of the Origin of Monocotyledons 
of the seedlings examined that the absence of intermediate 
links is of little weight. 
The Anemarrhena type of vascular structure is bisym- 
metrical throughout, and suggests a double origin for the 
cotyledonary members. 
The vascular symmetry of the seedlings examined from 
other Monocotyledonous families can be either derived from 
a Liliaceous type, or shown to be equally bisymmetrical. 
In the second Part I have described the vascular structure 
of a number of seedlings belonging to the Ranunculaceae 
which possess cotyledons more or less completely united 
to each other. When the united cotyledons are symmetrical 
with regard to the plumular axis — as in Eranthis hiemalis , 
Delphinium sp., and Anemone coronaria — their vascular struc- 
ture is bisymmetrical, and that of Eranthis bears a close 
resemblance to the structure of Anemarrhena. When the 
cotyledonary member is unilateral, as in Ranunculus Ficaria , 
its vascular structure is asymmetrical with regard to the axis. 
The strength of this comparison does not depend wholly on 
the suggestion of a real genetic relationship between Anemar- 
rhena and Eranthis for example, though I am inclined to 
think such a relationship probable, but rather lies in the fact 
that a partial union between two cotyledons does actually 
give rise to a reduced vascular system which bears a strong 
likeness to that existing in Anemarrhena and Albuca , a system 
already shown on comparative grounds to be in all probability 
the original of other Monocotyledonous types. 
The derivation of a seedling with unilateral vascular sym- 
metry, such as that of Zygadenus elegans , from a symmetrical 
form like Anemarrhena , has been justified by the examination 
of vascular systems intermediate between these extremes. 
The actual genealogy of Zygadenus is still of course con- 
jectural, but the a priori probability of such a descent is 
certainly increased by the analogy with Ranunculus Ficaria. 
The origin of the cotyledonary member in this species has 
already been fully discussed (p. 63). The conclusion there 
drawn from its external characters is that it has been formed 
