tkANSACxtoNS OP SElCttO?? K. 913 



Mociern Monocotyledons show no sign of having been' reduced from Blcotj- 

 ledous. The embryo of the Palm is precisely the same as that of any other 

 typical Monocotyledon. Palms are, of course, very far from being reduced, 

 and the same may be said of any other Monocotyledons. The primitive Angio- 

 sperm must have had alternate leaf-arrangement, especially if it were derived 

 from a form analogous to the Ferns. Hence if the dicotyledonous embryo 

 repeats the phylogeny of groups, the two opposed cotyledons cannot be primary, 

 but must be derived by dichotomy of a single cotyledon ; they cannot be derived 

 by approximation of two alternating leaves, for there is no stem in existence upon 

 which they could alternate at the time when they first arise. Reduction is out 

 of the question in such an advanced group as Dicotyledons ; moreover, there is no 

 embryonic type, characteristic of a group, from which sucli a supposedly reduced 

 dicotyledonous embryo could have been derived. That the dicotyledonous condition 

 is not primary, but that the two cotyledons really represent a single- dichotomised 

 member is shown by the fact that in plants with alternate leaves the two opposed 

 cotyledons are immediately followed by a single leaf about equal in size to the 

 two cotyledons together ; the single cotyledon has dichotomised and ensheathed 

 the plumule, this process being best carried out by the two halves becoming 

 opposite and distinct leaves. Cases observed in seedlings of Cheiranthm, &c., 

 support this. 



If the monocotyledonous condition is derived and reduced, then we ought to find 

 frequent cases of reversion to the dicotyledonous condition ; but this is, I believe, 

 unknown, whereas the converse is common, viz., the occurrence of dicotyledonous 

 seedlings with a single cotyledon. 



The Pseudo-monocotyledons afford cases where such reversionary Iprocesses 

 have become^.cefZ. These are true cases of reduction. The cotyledon of Mono- 

 cotyledons is homologous with the foliage-leaf of this group, as] is shown by the 

 fact that in Juncacete, Fistia, and Sparganium, the first one to eight foliage-leaves 

 develop in the same way as the cotyledon, i.e., each is terminal to the stem- 

 segment and dominant over it. Reasons are given for thinking that this structure 

 does not necessarily represent a reduction due to the aquatic habit. 



If these first few terminal foliage-leaves are homologous with the cotyledon, aa 

 is obvious, they must also each be formed by fusion of two opposite leaves, as is 

 supposed to be the case with the terminal cotyledon. Yet it must be conceded 

 that they are similar in every character save position to the remaining (lateral) 

 foliage-leaves of the plant. Hence it is highly improbable that the first and the 

 later formed foliage-leaves should be so diff'erent in origin ; and it is little short 

 of absurd to suppose that the typical foliage-leaf of a Monocotyledon repre- 

 sents in origin a compound, while that of a Dicotyledon represents a simple 

 organ. Yet this is the logical consequence of the fusion theory as advocated by 

 Miss Sargant. 



Anatomy. 



The primitive Angiosperm probably possessed a scattered system of vascular 

 bundles in its stem, due to possession of large leaves ; these probablv grew indi- 

 vidually in size by means of secondary thickening. Many Dicotvledons show 

 rudiments of this scattered arrangement in their stems in the form'of medullary 

 bundles; where it has vanished from the stem it often persists in the leaf-petioles. 

 This ancestral character could not possibly be exhibited by the seedling, owing 

 to the kind of space-relationships prevailing and absence of large leaves at that 

 stage. The argument from ontogeny is therefore useless in this connection. 



The bisymmetry of the vascular structure of the cotyledon of Anemarrhena 

 as pointed out by Miss Sargant, is due to the cotyledon being terminal, not to 

 its being the result of fusion of two organs. The structure of the cotyledon of 

 Eranthis is due to the same fact. 



Floral Structure. 



Pleiomery is the primitive character in the flower, at least aa reo'arda 

 the sporophylls. In those orders in which pleiomery obtains — c.y., Palmse 

 1908. 3 jt 



