650 Wieland — American Fossil Cycads. 



The structure of the Pachytesta vascular system is, in 

 fact, much too highly developed, much too reminiscent of 

 stem and leaf tracheidal organization, to permit the 

 assumption of a uniformly direct evolution of spores and 

 spore coats into seeds to go unchallenged. Were no 

 transitions from staminate to " unessential " organs or 

 envelopes anywhere in evidence, were fusions of fertile 

 organs not such omnipresent features of flowers, and 

 finally were the ampliivascular -flowers and the amphivas- 

 cular seeds less in evidence in ancient, and more frequent 

 in modern times, the fusion theory of seed and flower 

 would be more difficult to defend. 



But let the seed of Gnetopsis be further recalled. 

 Solms, in commenting on the view that the loose apical 

 tissues and the attached long feathery filaments were 

 devices for both wind and water transportation, remarks 

 that ■ i we cannot grant more than this ' ' ! Similarly 

 botanists apparently find difficulty in admitting that any 

 explanation or theory of the origin of seed coats can also 

 have a bearing on floral organization. But a fair atten- 

 tion to the facts here briefly outlined with due consid- 

 eration of the structures cited, and especially their 

 appearance in geologic time, emphasizes the larger truth 

 that seed envelopes and floral structures are not of uni- 

 formly direct origin. It must be admitted that either 

 fertile or sterile pseudovarian envelopes like that of 

 Gnetopsis could also arise long antecedent to the 

 development of seed coats comparable to those of 

 Gnetum, or Cycadeoidea, or Phy so stoma. And this pos- 

 sibility suggests Paleozoic, not Mesozoic development of 

 Angiospermous seeds and flowers. The manner in which 

 essentially simple courses of change progressing more 

 or less continuously in all the ancient lines, resulted in 

 diverse seed and floral structures, thus comes within 

 the scientific vision. 



