1903.] on the Origin of Seed-bearing Plants. 345 



In Heterangium, for example, a genus also investigated by William- 

 son, leaves and roots resemble those of the previous genus, but the 

 stem is more obviously Fern-like, agreeing in its earlier stages with 

 that of a Gleichenia, but acquiring, with advancincr age, a zone of 

 secondary wood and bast of the Cycadean type. This plant like- 

 wise bore foliage of the SpTienopteris form (^S. elegans). 



In Medullosa, on the other hand, to which the Alethopteris and 

 Neuropteris foliage belonged, the primary ground-plan of the tissues 

 in the stem is like that of a complex Fern, but the structure of 

 leaves and roots, and the secondary structure of the stem itself, is 

 almost puiely Cycadean. And we might continue the list much 

 further. Wherever one of these quasi-Ferns has been examined 

 anatomically, a similar combination of characters has been found. 

 It may be pointed out in passing that while many of these inter- 

 mediate forms lead on towards the Cycadophyta themselves, others 

 approach more nearly to the extinct family Cordaiteae, and indicate 

 that they also, though so different from Ferns in habit, may yet have 

 sprung from the same stock. 



But so far the positive evidence has been wholly anatomical, and 

 botanists are not yet altogether in agreement as to the value of 

 anatomical characters. The anatomist very naturally thinks that 

 there is nothing like anatomy, but the pure systematist will not be 

 satisfied without the characters on which he has been accustomed to 

 rely, and his faith in which has been so amply justified, those namely 

 drawn from the reproductive organs. Darwin, however, who neglected 

 nothing, was fully alive to the importance of anatomical evidence ; he 

 expresses his interest in an anatomical character in an amusing way 

 in one of his lately published letters (1861), saying, " The destiny 

 of the whole human race is as nothing compared to the course of 

 vessels in Orchids ! " 



Until the present year, we had no satisfactory knowledge of the 

 fructification in any one of the Cycadofilices, as we now call them, of 

 the Palaeozoic period. There is, it is true, some reason to believe 

 that a form of fructification with long tufted spore-sacs belonged to 

 Lyginodendron, but we know nothing as yet as to the details — it may 

 prove to represent the male reproductive organs of the plant. Among 

 the unidentified seeds of the Coal Measures, there are some — the great 

 seeds known as Trigonocarpon — which are not only associated with 

 Medullosa, but which show a certain structural resemblance to some 

 of its tissues. But still the indications were slight — so slight that 

 Professor Zeiller of Paris, than whom there is no higher authority, 

 has recently expressed a doubt whether these Cycadofilices were, 

 after all, anything more than a peculiar group of Ferns. 



Within the last few months, however, an altogether new light has 

 fallen on our subject. Among the seeds discovered by Williamson 

 in the English Coal Measures were three species which he placed in 

 his genus Lagenostoma. These, as we shall see, are characteristic 

 seeds of complex structure. One of them, named L. Lomaxi by 



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