

1920] 



CRIBBS—TODEA BARBARA 



291 



These are interpreted as being indicative of 



5. The cortical sclerenchyma is apparently of root origin, and 

 is extended to the stem cortex from the primary root or from those 

 which develop later in association with leaves. 



6. An endophytic fungus is frequently found in the root cortex. 

 It was observed to gain entrance through root hairs and through 

 newly formed epidermis at the edge of the root cap. 



7. A phyllotaxy represented by the fraction f is most fre- 

 quently found in the young plant. A f arrangement was recorded 

 in addition to a few cases of irregularity. 



8. Leaf traces usually are endarch while in the stem cortex, 

 and the protoxylem elements, which at first form a narrow band, 

 spread out on the adaxial embayment which occurs in the metaxy- 

 lem higher up in the petiole of the leaves. 



■ 



9. Typical mesarch bundles have been observed in the petioles 

 of early leaves. 



the ancestral condition, and in fact present the type of arrangement 

 found by Kidston and Gwynne-Vaughan to be characteristic of 

 Kalesskya and Thamnopteris, Upper Permian representatives of 

 this family. 



10. The transversely elongated phloem elements are derived 

 from periclinal divisions of the pericycle, and, as recorded by 

 Seward and Ford, are sieve tubes which, in the organization of 

 the stele, appear considerably later than the protophloem. 



ii. No instance of phloem within the medulla or central 

 parenchyma was found at any level in the young stele. 



12. The endodermis is continuous over the primary root, foot, 

 and early stem. At no place in the young stem does it turn in 

 through the gaps or embay ments in the xylem. 



13. Internal endodermis could not be demonstrated at any 



stage in the young stele. 



14. The earliest parenchyma to appear within the xylem is 

 composed of elements with pointed ends, whose caliber and length 

 are very similar to the xylem elements, and conspicuously unlike 

 the cortical cells. 



15. No sclerenchyma was observed in the medulla up to the 

 time of departure of the fourteenth leaf trace, although paren- 



chyma cells with included resinous substances were quite abundant. 



