488 STUDIES IN SEEDS AND FRUITS 



at present fulfilling no useful function and offering, as he adds, interest- 

 ing indications of the past history of the plants [A Contribution to our 

 Knowledge of Seedlings^ Internat. Sci. Ser., vol. Ixxix. p. 159). Though 

 one can imagine repressive conditions w^here the plant w^ould be driven 

 to utilise these rudiments of leaves, it is necessary to remember Dr 

 Goebel's warning that arrested organs do not necessarily represent 

 organs that were fully developed in the ancestors of existing forms, and 

 that it is invalid to assume that functionless organs are always only the 

 vestiges of earlier completely formed ones, it being quite a general rule 

 that many more primordia are laid down than become functional 

 {Organography of Plants^ i. 61). I am afraid, however, that the 

 argument from rudimentary organs would not assist my theory, 

 since one can point to cases amongst Barringtoniae and Guttiferae, 

 where the hypocotylar axis becomes the storehouse of the food- 

 reserve and the cotyledons are represented by functionless scales. 

 The last word on the subject belongs to the student of development, 

 and I notice with some satisfaction Dr Goebel's statement that 

 cotyledons proceed from the unsegmented primordium of the embryo 

 and not, as with later leaves, out of the vegetative point of a shoot 

 {Ibid.^ ii. 400). 



It is possible that the results of future investigation will support 

 the view that the retrogression may extend further back than the 

 seed-stage as we know it on this planet, and that the dual organism 

 that seems to be represented in the combination of endosperm and 

 embryo in an albuminous seed may be spHt into its two primal 

 parts, thus offering starting-points for two independent lines of plant- 

 development in different worlds. 



NOTE 20 (pp. 26, 35). 



Whilst preparing the appendix after the rest of the work was printed, 

 I found it more convenient to place the materials originally intended 

 for this note in Note 28 (p. 494). 



