1 74 Hill . — On the Seedling-Structure of certain Piper ales. 
the fusion of two cotyledons, then, bearing in mind the resemblances 
between the Ranunculaceae and certain Monocotyledons, and between the 
Piperaceae and the Araceae, it may be argued that the Monocotyledons are 
diphyletic. 
We may, with Miss Sargant, consider that the transition phenomena 
of seedlings have a phylogenetic value ; and it is clear that the type of 
transition herein described is not uncommon in Dicotyledons, so much so, 
indeed, that Tansley and Thomas 1 remark that £ the importance of this 
simple and striking type of hypocotyledonary structure is sufficiently 
apparent from its uniformity in the orders named. The temptation to 
regard it as of phylogenetic importance in relation to the Dicotyledons as 
a whole, already strong in view of its occurrence in the almost certainly 
primitive Ranunculaceae and their allies, is increased by its discovery in 
the Piperaceae.’ This temptation is doubtless strengthened by the occur- 
rence of the type in the Labiatae and Centrospermae. Further, the work 
of Miss Sargant and Chauveaud shows that a similar type obtains in 
different orders of the Monocotyledons ; Chauveaud 2 , in his work on Finns 
maritima, has described features identical with some of those of this 
particular type as it occurs in Angiosperms. The differences which obtain 
may be looked upon as modifications due to the increased number of 
cotyledons in Pinus, and although our knowledge of the seedling anatomy 
of these plants is decidedly scanty, it is probable that this modified type 
occurs in other Gymnosperms. Thus the evidence afforded by transition 
phenomena, if a phylogenetic value be assigned to it, supports all the above 
contentions. Hence it does not appear, from the facts at our disposal, 
that this evidence helps in the slightest degree in the elucidation of the 
phylogeny of the Angiosperms. 
But do the transition phenomena yield data of phylogenic importance? 
Further research will show ; in the meantime, it may not be considered 
inappropriate to draw attention to a few points. Miss Sargant has shown 
that much variation obtains in this respect in the Liliaceae, a similar 
diversity has been found by Wright 3 to obtain in different species of 
Diospyros, the present work shows that the details of the transition in the 
Piperaceae are anything but rigid, and, finally, the writer has found that 
there is seemingly much variation in the Centrospermae. 
It will probably be agreed that features taken as indicating phylogeny 
should be sufficiently rigid to withstand the influence of varying conditions, 
both internal and external. 
Is this the case in these transition phenomena ? 
1 Loc. cit., p. 106. 
2 Chauveaud, M. G. Passage de la disposition primitive a la disposition secondaire dans les 
cotyledons du Pin maritime (Pinus maritima). Bull, du Mus. d’Hist. Nat., 1902, No. 7. 
3 Wright, H. The Genus Diospyros in Ceylon ; its Morphology, Anatomy and Taxonomy. 
Ann. Roy. Bot. Gard. Peradeniya, ii, 1904. 
