292 Allgemeines. 



(2) In an earlier form, Lagenostoma from the Lower 

 Goal Measures, we have a type of seed shov/ing marked 

 and unusual peculiarities, which are next described, Compared 

 with the ordinary palaeozoic type of seed, Lagenostoma seems 

 peculiar in the lack of tracheal supply beneath its pollen 

 Chamber. Also while it resembled Cycads in the considerable 

 area of „fusion", which obtains between the nucellus and testa, 

 it is marked by special peculiarities, of which the presence of 

 a „canopy", a structure whose homology and function is at 

 present obscure, is the most remarkable. 



(3) The main difference between the seeds of recent Cycads, 

 and those of the ordinary Palaeozoic type is found in the fact 

 that only at the apex are the nucellus and integument free from 

 one another. The distribution of the vascular System in the 

 Cycadean ovule is discussed, and it is pointed out that the 

 varying types of chalazal branching seem consistent with the 

 assumption that the whole of the body of the ovule, below the 

 level at which the nucellus becomes free, is phylogenetically 

 younger than its apical parts — that between the original ovule 

 and its Insertion a new region has been intercalated. The 

 main significance of this intercalation is probably nutritive. 

 In the Cycadean ovule there is also a marked retreat of the 

 nucellar bundles from the pollen Chamber, since they are no 

 longer needed so urgently as in the palaeozoic seeds, mainly 

 because the pollen effects haustorial attachment in the nucellar 

 tissues, obtaining thus the water required in further deve- 

 lopment. 



(4) The vascular anatomy of Torreya is peculiar and 

 isolated among recent plants, and represents an archaic type. 

 The morphology and embryology of this seed is explained, 

 and the remarkable course of its bundles is compared with that 

 found in Cycads and in palaeozoic seeds. 



Whilst the consideration of these seeds from the palaeozoic 

 rocks, together with those of recent Cycads and Taxaceae 

 tends to confirm the view of their common origin, it is evident 

 that even the oldest forms show a marked advance on the 

 condition that probably obtained in their pteridophytic ance- 

 stors. The condition of vascularity in a fern-sporangium, which 

 is known to have actually existed, among fossil plants, may 

 have been an important antecedent to the evolution of the 

 vascular nucellus that played so considerable a part among 

 the earlier Gymnosperms, and from which it may be reasonably 

 supposed the ordinary Goniferous type of nucellus has been 

 derived. Arber (Cambridge). 



Scott, D. H„ The Origin of Seed-bearing Plants. (A 

 lecture delivered at the Royal Institution of Great Britain. 

 May 15. 1903. p. 1 — 14.) 



It is pointed out that some four-sevenths of all recent plants 

 are seed-bearing as opposed to spore-bearing. Among such 



