Seedling Structure of Gy mno sperms. II. 209 
Tracing these strands downwards a, b, d, and e act as the bundles of half- 
cotyledons. The trace d may be placed on a plane slightly higher than a , 
b , and e , since it possesses the dignity of a resin duct. As regards the other 
bundles, g soon loses its smaller group of xylem elements and combines 
with f to form a pole of the root, the intervening half-bundle of /having 
died out (Diagram 7, Figs. 2-5). The two seed-leaves to which they belong 
are therefore half-cotyledons. The bundle c was of a somewhat undecided 
character, the phloem of the smaller portion of the bifurcated bundle 
speedily disappeared (Diagram 7, Fig. 2), and, at a lower level, the corre- 
sponding xylem-mass followed suit (Diagram 7, Fig. 4). From this it 
would be supposed that it would ultimately act as the strand of a half- 
cotyledon, but at a still lower level (Diagram 7, Fig. 5) the missing xylem 
reappears and the whole bundle forms one pole of the tetrarch root. 
Series M had seven cotyledons, but it is only necessary to draw 
attention to the bundle of one of them. This strand showed the bifurcation, 
but the half-bundle of one side soon disappeared ; it would therefore be 
imagined that its performance would be that of the trace of a half-cotyledon, 
but this was not the case. The whole of the remaining phloem passed over 
and fused with the similar tissue of the adjoining bundle, and a rearrange- 
ment of the xylem took place so that the protoxylem became exarch in 
position. This is something like what obtained in bundle c of series H of 
this same plant. 
Pinus maritima. The structure of the seedling of this plant has been 
worked out by Chauveaud, 1 whose account shows that this species resembles 
P. sylvestris , P. contorta , var. Murrayana , & c., very closely as regards the 
features under consideration. 
He points out that there is no constant relation between the number 
of cotyledons and the root-structure ; for instance, a plant with five seed- 
leaves may have a pentarch root, while a seedling with seven cotyledons 
may have a tetrarch root-structure ; generally, the seed-leaves are more 
numerous than the bundles of the root. Further, he recognizes different 
kinds of cotyledons ; the primitive ones (corresponding to our whole- 
cotyledons), the bundles of which show a vascular rearrangement, viz. the 
bifurcation of the vascular tissue and the assumption of the exarch position 
by the protoxylem, as they are traced from the apex downwards ; and the 
non-primitive seed-leaves (corresponding to our subsidiary-cotyledons), in 
the bundles of which no such rearrangement obtains, they being collateral 
throughout. They are further characterized by the absence of a resin canal. 
Dangeard 2 also briefly alludes to this species, and gives figures of the 
seedlings and the course of the bundles. 
■ Chauveaud : Passage de la disposition primitive a la disposition secondaire dans les cotyledons 
du Pin maritime. (Extr. Bull. Mus. Hist. Nat., Paris, 1902.) 
2 Dangeard: Le Botaniste, iii, 1892. 
