564 S topes. — On the Double Nature of the Cycadean Integument . 
One or two further details may be worthy of mention. In the above 
quotation it is stated that ‘The canopy of a L agenostoma may well have 
undergone simplification into the hard integument of a Cycadean seed.’ 
I had previously looked upon the stone layers as belonging morphologically 
to the outer flesh, and did so on the ground that it was generally much 
more difficult to draw a boundary line between these two layers than 
between the stone and the inner flesh, which are always distinct ; that the 
bundles of the outer flesh are in some cases partly embedded in the stone 
layers while the bundles of the inner flesh are distinct from it ; and also 
that in the young ovule differentiation and sclerification of the stone cells 
start in the layers on the inner side and extend in an outward direction. 
In support of the other view, however, are the facts that the canopy tissue 
is hard, and that in Lagenostoma ovoides there are definite thickened cells 
in the outer zone of the integument. 
It is very clearly marked in many Cycads that the stone has at least 
two layers, an inner one of mainly vertically running stone cells as in the 
integument of L. ovoides , and an outer one of mainly horizontally running 
stone cells. It may be that it is in the junction between these two layers 
of cells that we get the actual plane of fusion between the two integuments; 
the connexion between the outer stone layers and outer flesh in my eyes 
is too strong to allow of their morphological separation. 
It is true that I have found in Encephalartos Barteri and other cases, in 
the stone freed from the flesh, a strong superficial likeness to the ‘ canopy ’ 
of Lagenostoma . This appearance, however, is correlated with the bending 
away from the stone of the bundles of the outer flesh as they go towards 
the micropyle, and although superficially it is strongly reminiscent of the 
canopy, yet as it is connected with the outer and not the inner series of 
bundles it can hardly be homologous with the canopy which belongs to the 
inner integument. Further, the well-marked ridges in the ripe stone, seen 
so clearly in Macrozamia spiralis , Encephalartos Altensteinii , &c., are also 
the result of the close proximity of the bundles of the outer flesh to the 
stone, and these ridges always correspond exactly to the bundles, the 
number thus varying according to the number of the bundles, so that there 
are but two in Cycas, twelve in Macrozamia and so on. They do not thus 
correspond to the joined edges of leaflets as some exponents of the foliar 
theory of the ovule suggest, but may rather represent the vascular midrib 
of the lobes of the ‘ cupule ’-like covering. In this way they may perhaps 
indicate the number of lobes in this covering, except in a case where 
definite reduction has taken place, as in Cycas, where the only remnant of 
the original radio-symmetry and many-bundled condition of the outer flesh 
is found just below the base of the seed. 
These various considerations, combined with those before stated 
relative to the development, lead me to consider that at least the outer 
