[.897. ] 
XV. The Anatomy of Welwitschia mirabilis, Hook. f., in the Seedling and Adult States. 
Forming Report No. 2 of the Percy Sladop" Memorial Expedition to South-West 
Africa, 1908-1909. - By M. G. SYKES, Girton College, Fellow of Newnham 
College, Cambridge. (Communicated by Prof. H. H. W. Pearson, Sc.D., F.L.S.) 
(Plates 34 & 35 and 5 Text-figures.) 
Read 21st April, 1910. 
CONTENTS. Page 
mulroduotory ooe aa e e Le x0 a a ais ris VCI peewee IDA 327 
Section, L. Development of Outward Form 445. esee eie ERXRRS 328 
II. The Root Bystét cocci ied IS ut zd aa a i el ES 334 
III. The Structure of the Ridges and Young Inflorescences ........ 337 
= IV. The Cotyledonary Buds (Lobes of the Crown) ................ 339 
: V. Transition Phánomeng is 091.502). 48 4 ies gay ste soto as 340 
; VI. Comparison of the Transition Phenomena with those in other 
Gymnosperms iroso iade ie UE A eas Va RU pd VAR a Ain ein 344 
VII. Centripetal. Xylem in the Seedling is: sorier toi hne 946 
VIII. Anatomy of the Adult Hypocotyledonary Stem .............. 347 
IX. General Conclusions .,...:5 51624549 43R RE A42 is ores Eae 348 
ALTHOUGH the structure of this interesting and isolated genus has already been 
investigated by various workers *, it seemed advisable that it should be further studied in 
the light of recent research. A large number of seedlings and young plants (collected 
and preserved during the recent Percy Sladen Memorial Expedition in South-West 
_ Africa) have been most kindly placed at my disposal by Professor Pearson. In addition 
to these, I have examined two younger seedlings grown in the Cambridge Botanic 
.. Garden, 
The investigation of this material, while confirming the greate 
of the seedling anatomy given by Bower + in 1881, has also broug ht 
Points of interest, which appear to be of some importance. In addition to the 
description of the facts contained in that memoir, this paper includes short discussions 
of theoretical questions on which evidence is obtained from a study of the mode of 
growth and the structure in Welwitschia, and an attempt has been made to draw 
attention to such characteristics in the structure of this plant as are of especial interest 
™ Connection with recent work. 
Tam indebted to Professor Pearson for his kind interest in this paper, and to Mr. D- 
‘today for valuable assistance in the preparation of the text-figures. 
r part of the account 
ht to light additional 
* Hooker, 1863; Bower, 1881; de Bary, 1884, &c. 
+ Bower, F. O., 1881, I. & IL 
SEC 3c 
OND SERIES.— BOTANY, VOL. VIL. 
