On the Classification of Seed-Leaves. 
BY 
T. G. HILL 
AND 
E. de FRAINE. 
I N a highly interesting study of Syncotyly and Schizocotyly,Mr. Compton, 1 
whilst in agreement with our general conclusions, 2 adversely criticizes 
us with regard to what we have termed { subsidiary cotyledons \ 
The classification of cotyledons was a by-way in our main work on 
seedling-structure, and one to which we do not attach a vast amount of 
importance ; but since Mr. Compton, who has much first-hand knowledge 
of the subject-matter, finds difficulties in understanding our position, it is 
not unlikely that others also will find difficulties ; hence it appears desirable 
to write a few words in reply. 
It was found, in our work referred to above, that although the seed- 
leaves, more especially of the polycotylous Gymnosperms, might be exactly 
similar externally, the behaviour of their vascular bundles in the transition 
phenomena might be very different. 
i. In some cases the vascular strand of a cotyledon gave rise to one 
pole of the root-structure. 
2. In other instances, the vascular bundles of two adjacent cotyledons 
gave origin to one pole of the root-structure. 
3. And in some examples, the trace of a seed-leaf played no part in the 
transition phenomena, but joined on to any adjacent vascular tissue in no 
definite fashion. 
From the constant occurrence of these phenomena, the seed-leaves 
were respectively divided into three classes : (i) whole cotyledons, (ii) half- 
cotyledons, and (iii) subsidiary cotyledons. 
We expressly stated that this classification was based on the behaviour 
of the seed-leaf traces in the transition region . 3 Whether we were justified 
1 Compton, R. H. : An Anatomical Study of Syncotyly and Schizocotyly. Ann. Bot., 1913, 
vol. xxvii, p. 793. 
2 Hill, T. G., and de Fraine, E. : On the Seedling Structure of Gymnosperms. Ann. Bot., 1908, 
vol. xxii, p. 689 ; 1909, vol. xxiii, p. 189. 
3 Hill and de Fraine: Seedling Structure of Gymnosperms. II. Ann. Bot., 1909, vol. xxiii, 
p. 221. 
[Annals of Botany, Vol. XXVIII. No. CX. April, 1914.] 
