674 CONCLUSION 
definite “adaxial” surface is presented towards it. It thus appears that the 
most constant features of the embryo in Pteridophytes are: (1) the origin 
of the axis in relation to the initial polarity of the embryo, and (2) the 
orientation of the first leaves relatively to it. These facts once recognised 
must needs take a premier place in Pteridophyte embryology. The 
embryo is thus presented to the mind as consisting essentially of an axis 
or spindle, liable in the different types to varying proportions of length 
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Fic. 359. 
Diagrams of embryos: the suspensor is cross-hatched; the hypobasal hemisphere 
dotted, and the epibasal clear. A=Selaginella spinulosa. B=Selaginella Martensit. 
C=Lycopodium Selago. D=Lycopodium cl E=Lycopodium cer: = 
Lsoetes. G=Equisetum. H=Adiantum. c=cotyledon; af=apex of axis; r=root; 
hyp=hypocotyl; /=foot ; s=suspensor. These diagrams place various of the divergent 
types described in the text in juxtaposition, and thus bring into prominence their points 
of similarity and of difference. 
and breadth, upon which the other parts are inserted as appendages: 
the leaves with a more regular relation, the roots with less regular 
relation, and the haustoria or tubercles being occasional. In cases 
where a suspensor is present this constitutes the organic base, while 
the stem-tip forms the organic apex of the spindle, which is itself 
built up from the suspensor, the hypobasal, and the epibasal tiers. In 
cases where no suspensor is formed the relations of parts are still the 
same, but the base is formed from the centre of the hypobasal. tier; 
often, however, the latter is specially developed as an haustorial foot, 
or disguised by the early origin of a root. The spindle thus defined is 
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