746 



A TEXTBOOK OF THEORETICAL BOTANY 



towards the middle. Such inrolling suggests a relic of the circinate vernation 

 of Ferns, traces of which, as we have seen, still linger in the Cycads. 



Fig. 749. — Ginkgo biloba. Seedling 

 developnient. A, Seedling with 

 cotyledons still embedded in the 

 seed coat. B, Longitudinal section 

 of the seed with straight embryo 

 embedded in endosperm. C to E, 

 Series of youngest leaves showing 

 the development of the bilobed leaf. 



{From I'elenovsky, " Verghichende 

 Morphologic der Pflatizen.") 



A peculiarity of Ginkgo which suggests a relic of pinnation in the leaf is 

 this ; the first epicotyledonary leaves are merely forked scales. The second 

 pair have a bilobed lamina, at the base of which are two lateral prongs, 



