794 Compton. — An Anatomical Study of 
cases in which the phenomena in question are taking place, so to speak, 
before our eyes. Moreover, it is impossible to judge how much theoretical 
weight to attach to any phenomenon, teratological or otherwise, before it 
has been adequately investigated ; and cases such as the present cannot be 
dismissed on a priori grounds. 
The paper will consist of two parts: the first will deal with Syncotyly, 
the second with Schizocotyly. 
Syncotyly. 
There exists a small and scattered literature on this subject, for the 
most part simply recording instances of the anomaly. The most important 
investigation of the phenomenon is that of de Vries , 1 who dealt with it from 
the point of view of its heritability. From the morphological and ana- 
tomical point of view, however, syncotyly has not been studied, so far as I 
know : it is from this standpoint that I have approached the subject, partly 
from its intrinsic interest and partly in the hope that it might shed light 
upon the origin of the Monocotyledons. The following pages are the 
results, at present very incomplete, of an examination of some cases of 
syncotyly : owing to the comparative rarity of the anomaly the research is 
necessarily prolonged, but the future may furnish fresh material for study 
and render possible an amplification of what can be written upon the 
subject at present. 
I shall proceed to describe the structures which have been observed in 
the material available, and shall then enter into a discussion of certain pro- 
blems arising out of the investigation. 
SWAINSONA Cadelli (Leguminosae). 
The anatomy of the normal dicotylous seedling of this species is 
described in my paper on the Leguminosae . 2 The root is triarch, and each 
cotyledon takes one whole root xylem united with half of the third inter- 
cotyledonary xylem bundle. 
A single syncotylous seedling was examined, the two cotyledons being 
fused to the tips, with only a very shallow apical sinus marking the line of 
union (Fig. i) : a double system of vascular bundles was evident in the seed- 
leaf. The root was triarch, as in the dicotyl, and the whole process of 
transition took place in precisely the same way : the sole difference from 
the type being that both double bundles entered the single seed-leaf (Fig. a). 
The subsequent branching and anastomosing of the bundles took place in 
the usual fashion. 
This is an example of the simplest type of syncotyly, in which there is 
practically no modification of the vascular anatomy introduced by the 
lateral union of the two cotyledons, even though this be complete. The 
simplicity of the bundle system probably accounts for this. When we 
1 de Vries (’95, ’ll). 2 Compton (’12 b ), p. 44, and PI. VI, Fig. 93. 
