414 BOTANICAL GAZETTE [DECEMBER 
Tieghem, Poirault, and Jeffrey, in the genera Ophioglossum, 
Botrychium, Equisetum, Ranunculus, etc. Very lately Boodle, 37; 38 
has called attention to an interesting series of central cylinders 
in the family Schizaeaceae. Aneimia Phyllitidis has a ring of 
separate bundles, each with a band of xylem surrounded bya 
phloem, pericycle, and endodermis of its own; A. Mexicana has 
a complete ring of xylem in the internodes with external and 
internal cylinders of phloem and endodermis ; Schizaea has a 
ring of xylem surrounding a central pith, but no internal phloem 
or endodermis. It is likely that here, too, the Schizaea type is 
derived from the Aneimia type by degeneration. In the Hymen- 
ophyllaceae likewise, every grade is found from the case in 
which the phloem of the solid stele forms a complete ring to 
that in which it is developed on one side only. 
After examining a number of comparatively young specimens 
of O. Claytoniana, 1 am somewhat doubtful if the study of 
the development of this species will throw any further light on 
the subject of morphology; but for O. regalts 1 am more hope- 
ful. Nevertheless, aside from further developmental proofs, I 
incline to the view that O. cinnamomea possesses the most 
primitive type of central cylinder. I again recapitulate the 
reasons : 
1. The opposite view demands a very plastic central cylinder 
in one species alone, not differing very greatly in habit from the 
others. 
2. There would still remain phenomena that the opposite 
view could not explain. 
3. There are no facts of development even in analogous 
cases to support the opposite opinion. 
4. The view adopted here demands only slight changes, and 
those are of degeneration, to explain all the phenomena. 
5. There are precisely similar analogous cases of degenera- 
tion. 
6. Within the species O. cinnamomea itself, every phase of 
- 3 BOODLE: Stem structure in Schizaeaceae, etc. Brit. Assn. Dover, 1899. 
ea BooDLE: On the anatomy of the Hymenophyllaceae. Ann. Bot. 14: 455- 
