144 BOTANICAL GAZETTE [AucusT 4 
of the peduncle and of the leaf as evidence of the affinity of modern — : 
of mesarch primary wood is limited to no one group of plants, and | 
that its presence or absence is of no value as phylogenetic evidence. 
CONCLUSIONS 4 
The position of the protoxylem in the primary wood bundle of 
vascular cryptogams is very variable, for in all of the groups it may 
be almost anywhere in the strand. It is consequently of little 
value -in determining the relationship of any group to other groups 
or to the higher plants. A constant primitive feature in the vas- 
cular cryptogams, however, is the presence in the stem of cryptogamic : 
wood—centripetal xylem continuous with the protoxylem elements. — 
Whenever such a feature occurs in any of the higher plants, it can be 
used as evidence in tracing their affinity only with vascular cryp 
togams in general, not with any particular group of them. . 
I desire to express my thanks to Dr. M. A. CHRYSLER and to Mr. 
A. J. Eames for assistance in procuring material, and especially 1 
Professor E. C. Jerrrey for advice during the course of the work. 
This investigation was carried on in the Phanerogamic Labo 
tories of Harvard University. 
HYANNIs, Mass. 
. LITERATURE CITED 
1. BRoNGnrart, A., Observations sur la structure intérieure du Sigillaria elegans 
etc. Arch. Mus. Hist. Nat. I: 405-460. 1839. ‘ 
- MertTentus, G., Beitrige zur Anatomie der Cycadeen. Abhandl. Konigl. 
Sachs. Gesells. Wiss. '7: 565-609. 1861. a 
RENAULT, B., Structure comparée de quelques tiges de la flore Carbonifére- . 
Nouv. Arch. Mus. Hist. Nat. II. 2:213-248. 1879. 
4. Sotms-Lausacu, H. Grar zu, Palaeophytologie. Géttingen. 1887. 
Grson, R. J. Harvey, Contributions towards a knowledge of the anatomy 
of the genus Selaginella, Part I, the stem. Annals of Botany 8:133? 
pls. 9-12. 1894. . 
, Idem, Part III, the leaf. Annals of Botany 11: 123-155- pl. 9- 1601 
Scort, D. H., Studies in fossil botany. London, 1908, Part I. x 
1S) 
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