MEMBERS OF THE PLANT BODY 325 



guise and exhilnt their true nature' The proof of a theory' is 

 in the using; for the present it will be enough for us to have 

 gotten a prehminary idea of what the segment theory means 

 Avhen appUed to our typical plant. 



Other questions, closely connected with the foregoing one, 

 are, What members ma}^ a segment have? and, How may 

 these be distinguished under all their disguises? The flax 

 embryo, as we have seen, represents a segment reduced to 

 about its simplest terms. We here recognize an axial member 

 bearing lateral members, — the stem-part and the leaf -part, — 

 one impl^'ing the other. When the root-part appears we have 

 another member which is also axial, but differs from the 

 stem in being without leaves. As the root elongates there 

 appear near its tip numerous hair-like projections which 

 differ essentially from leaves in being merely superficial 

 outgrowths not continuous with the innermost parts as is 

 the case with leaves. Superficial appendages of this sort 

 often occur in other plants on the stem and leaves as well 

 as on the root. Such more or less hair-like outgrowths are 

 best regarded as parts of members rather than as members. 

 In the essential organs of the flower we meet with a difficulty 

 regarding the real nature of the pollen-sacs and ovules or 

 egg-sacs as we may call them. In the flax they both might 

 be taken to be parts of the peculiar leaves which we regard 

 as forming the stamens and pistil. But there are other plants, 

 as we shall see, in which an ovule appears on the very tip 

 of the stem or axis, while in some cases pollen-sacs seem to 

 grow directly from the stem. We can then hardly call such 

 organs parts of a leaf. On this account and for other reasons 



1 The theory of floral structure which Hkens a flower to a leaf-rosette 

 originated with the poet Goethe to whom it was suggested by seeing 

 a green rose such as occasionally appears in gardens. This theory has 

 proved to be a helpful means of understanding the relation of the various 

 parts of plants to the fundamental plan of structure; but as it tells 

 only part of the truth it has been somewhat misleading, and it requires 

 to be modified considerably from its original form to be in accord 

 with more recent views of vegetable morphology. As developed above, 

 however, it is believed that the theory will be found to avoid the un- 

 warranted assumptions which have brought into it discredit, and to re- 

 tain the features which have made it useful, wliile at the same time 

 such modifications are made as will render it a valuable means of con- 

 veying modern views. 



