100 _ BOTANICAL GAZETTE [FEBRUARY 
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Untersuchung. Sitz. Kgl. Akad. Wiss. Wien 78:165-201. pls. I-3. 1905. 
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Mém. Akad. Imp. Sci. St. Pétersbourg VII 19: adh: bk 1-11. 1872. 
24. ScHouTE, J. C., Die Stelar-Theorie. Groninge 
25. SCHWENDENER, 'S., Ueber Scheitelwachstum ie beceeees Wurzeln. 
Sitz. Kgl. Akad. Wiss. Berlin 1:183-199. pls. 6, 7. 1882. 
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Annals of Botany 14:497-525. pls. 28, 29. 1900. 
27. TANSLEY, A. G., and Lutuam, Miss R. B. J., On a new type of fern stele 
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EXPLANATION OF PLATES IX-XII 
With the exception of figs. 4, 5, 11-21, and 25, all drawings were made with 
the aid of an Abbé camera lucida and reduced one-half in reproduction. Abbre- 
viations are as follows: c, cotyledon; en, endodermis; /, leaf; Jb, leaf base; 
it, leaf trace; ms, medullary strand; pa, parenchyma; ph, phloem; pph, 
protophloem; pr, prothallium; px, protoxylem; r, root; rt, root trace; §, 
sieve tube; sf, stipule; x 
IG. 4.—Young sporeling attached to the prothallium, with the second 
leaf appearing. 2.5. 
Fic. 5.—Older sporeling, showing persistent leaf bases (Jb). 
1G. 6.—Transverse section his the cotelydonary ony showing 
ap yey cells among the xylem. X 400. 
G. 7.—Transverse section through the stele, showing apparent pith 
due is the simultaneous departure of the root trace (rf) and leaf trace (It) 
opposite epi <0 X 188 
IG, nsverse section of the same 50 » above fig. 7, showing phloem 
(ph) and ecient (en) cutting in a curve behind a leaf trace. X 188. 
9.—Transverse section of the same 4o above fig. 8, showing the 
seareue of the next leaf trace (/#) and a persistent cell of cortical parenchyma 
(pa). X 188. 
Fic. 1o.—Transverse section of the same 4o » above fig. 9, showing cortical 
parenchyma (pa) at the side of the stele, contrasting with xylem parenchyma 
in size. X 188. 
Fics. 11-21.—Diagrams of successive stages in the transition from PT? 
tostele to solenostele. : 
Fic. 22.—Transverse section from the inner surface of a dictyostelic 
bundle, showing endarch protoxylem, bands of parenchyma, sieve tubes, 
pericycle, and endodermis. «188 
