4 6o STUDIES IN FOSSIL BOTANY 



Renault's prescience has been fully justified by 

 subsequent discoveries ; possibly even the direct proof 

 of the existence of spermatozoids in fossil Seed-plants 

 may yet be obtained. 1 



The presence of a pollen -tube in the case of 

 Stephanospermum and other Palaeozoic Spermophytes 

 is very doubtful. Small papillae are occasionally 

 observed (as in the large pollen-grain shown in Fig. 

 173), but their significance is still uncertain. Some 

 further reference to the question will be made in 

 discussing the fertilisation of the Cordaiteae (Chap. XII. 



P- 543)- 



It is only in the case of Neuropteris heterophylla 



that we have, as yet, the direct proof that Neuropterideae 

 bore seeds ; as we have seen there is strong, though 

 less conclusive, evidence that the seed Trigonocarpus 

 Parkinsoni belonged to Medullosa anglica, which, ac- 

 cording to its foliage, was certainly an Alethopteris. 



A considerable mass of evidence, mainly from 

 association, has further been accumulated through the 

 extensive investigations of M. Grand'Eury both in the 

 Upper Coal-measures of Central France and in the more 

 ancient deposits of Belgium, Northern France, and the 

 Saar Valley. This observer, whose experience in such 

 researches is unrivalled, finds that the vegetative organs 

 of Neuropterideae, wherever there is evidence that they 

 grew in situ, are constantly associated with seeds of the 

 radially symmetrical type, such as rarely occur in 

 company with plants of any other group; he further 

 finds special types of seed in close association with 



1 Evidence on this subject is adduced in Prof. F. W. Oliver's memoir 

 " On Physostoma elegans," Ann. of Sot., January 1909. 



