Anatomy of Ter ato logical Seedlings . III. 341 
is of dual origin this position represents what would be, in typical dicotyls, 
the intercotyledonary plane. If, on the other hand, the single cotyledon is 
h.eterocotylous in origin it is obvious that there has been an increase of 
ninety degrees in the angle of divergence between that structure and the 
first epicotyledonary leaf. There is no evidence in support of this change, 
though, in view of the fact that the epicotyledonary primordia originate 
much later than the cotyledons, it is conceivable that the modification in 
the latter may have induced an alteration in the orientation of the former. 
The character of the epicotyledonary modifications themselves is 
wholly in favour of a syncotylous derivation, since the compression modifi- 
cations typical of the more advanced syncotyls are reproduced faithfully in 
the seedlings comprising the second group. 
It is worthy of note that in the monocotylous Ranunculus Ficaria and 
in all Monocotyledons proper 1 the seedling anatomy of which has been 
investigated, the insertion of the first epicotyledonary leaf is opposite that 
of the cotyledon. If this insertion is to be regarded as decisive in demon- 
strating a syncotylous origin of an apparently single cotyledon, then the 
Monocotyledons are undoubtedly of dicotylous origin. It must be 
remembered, however, that in embryonic tissues, such as are characteristic of 
an intraseminal stem apex, one is dealing, as Miss Sargant rightly empha- 
sized, with extremely plastic material, and it is readily conceivable that the 
explanation of such an insertion is to be sought along physiological rather 
than phyletic lines. The third alternative need not be discussed at length. 
If the material investigated had been represented by apparent heterocotyls 
only, the conception might have been possible, although it would have 
involved a suppression of the vascular continuity between the modified 
cotyledon and the radicle. In the face of the evidence supplied by obvious 
syncotyls in which a gradual suppression of one leaf of the basal epicoty- 
ledonary pair can be demonstrated the idea becomes untenable. 
It is of course realized that the evidence afforded by an anatomical 
study of teratological seedlings in a single species provides much too 
insecure a peg to hang a comprehensive theory upon, but one is perhaps 
justified in pointing out that, whichever view is adopted with regard to the 
origin of the second group of seedlings described, the result gives food for 
thought. If syncotyly is invoked, then we have, in a species normally 
dicotylous, teratological syncotyls in which all trace of double origin is lost : 
if, on the other hand, a heterocotylous origin is regarded as more probable we 
are faced with the fact that syncotyly and heterocotyly are possible within 
the limits of a single species. A comparison of the cotyledonary anatomy 
of the second group of seedlings with that of Ranunculus Ficaria reveals 
1 E. g. Albuca Nelsoni , Allium spp., Anemarrhena asphodeloides , Anthericum Liliago , Arisaema 
dracontium, Arthropodium cirrhatum, Arum maculatum , A. italicum , Chlorogalum -bomeridianum , 
Fritillaria imperialis, Hyacinthus romanus , Triglochin palustre , Zygadenus elegans. 
