292 BOTANICAL GAZETTE [october 



i 6. After the first organization of a definite medulla, short, 

 thickened xylem cells have been observed to be present on the inner 

 edge adjoining the pith. These elements, although thickened, 



were poorly lignified, contained some protoplasm and a degenerate 

 nucleus, had transverse or slightly obliqued terminal walls, were 

 usually in axial continuity above or below with parenchyma 

 elements, and when in contact with adjoining tracheae did not 

 develop the intercellular lacunae so characteristic of the protoxylem 

 and metaxylem of this family. These elements are considered as 

 belated xylem of vestigial character, and, because of their position 

 and relation to the internal parenchyma, are evidence of medullary 

 origin by stelar reduction. Cells of this type were not found in 

 either the petiole or root. 



17. The appearance of mesarch traces in basal leaves, a pro to- 



■ 



stele in the early stem, the similarity in topography of early xylem 

 parenchyma to xylem, the appearance on the inner border of the 

 xylem of peculiar short tracheids with transverse terminal walls, 

 the entire absence of internal phloem, the absence of internal 

 endodermis, and the complete unity of the endodermis (which 

 shows no indication of invagination) are all features in the ontogeny 

 of Todea barbara which are indicative of a protostelic ancestry. 

 These features assume a special significance when we can correlate 

 them with similar structures in primitive forms, and their recur- 

 rence in Kalesskya and Thamnopteris further validates the theory 

 of the protostelic origin of our living Osmundaceae. 



Drury College 



Springfield, Mo 



LITERATURE CITED 



1. Bower, F. O., The comparative examination of the meristems of ferns 

 as a phylogenetic study. Ann. Botany 3:305-392. pis. 20-24. 1889. 



2. , Apex of the root in Osmunda and Todea. Quart. Jour. Mic. Soc. 



2S:75- 1885. 



3. DeBary, A., Comparative anatomy of the vegetative organs of the 

 phanerogams and ferns. 1888 (pp. 278-280). 



4. Faull, J. H., The anatomy of the Osmundaceae. Bot. Gaz. 32:381-420. 

 pis. 14-17. 190.1. 



5. Gwynne-Vaughan, D. T., Polystely in the genus Primula. Ann. Botany 

 11:307-326. pi. 14. 1897. 



« 





