The Ontogenetic Development of the Stele in Two 
Species of Dipteris. 
BY 
HELENA DE BRUYN, 
Newnham College , Cambridge. 
With Plates LVII and LVIII. 
T HE material investigated was gathered by Mr. Tansley in 1901 on 
Mount Ophir in the Malay Peninsula. The amount of material avail¬ 
able was not very large, and often the series of sections were not quite 
complete, so that not all the stages wanted were obtained; enough facts, 
however, were gathered to form some conclusions on the development of 
the stelar structure. 
The plants investigated wer z Dipteris conjugata, Reinwardt, and D. Lob - 
biana , Moore. Both have a creeping rhizome with leaves going off in alter¬ 
nate rows. Fig. 3, PI. LVII, shows a young plant of D. Lobbiana\ the first 
leaves are divided once, in the latest formed a second dichotomy has taken 
place. The veins in the leaves branch dichotomously and anastomose, 
even in young leaves (.D. conjugata , Fig. 5; D. Lobbiana , Fig. 6, PI. LVII). 
In the adult stems of both species a solenostele is present. The anatomy 
of the stele of the mature plant of D. conjugata is fully described by Seward 
and Dale. 1 
Dipteris conjugata. 
Endodermis . Surrounding the steles of the young plants we find, in 
the first place, a layer of endodermal cells easily to be recognized by the 
dark contents of its cells. An endodermis consisting of cells with dark 
brown contents is a very widely spread phenomenon among Ferns, and endo¬ 
dermal cells with similar contents are even found in the fossil solenostelic 
Fern described by Miss Kershaw. 2 In the regions near the growing point, 
however, and sometimes also in older parts, the dark secretion is either 
absent or, owing to bad preservation or other causes, is not apparent, and 
1 Seward and Dale : On the Structure and Affinities of Dipteris. Phil. Trans. Roy. Soc., 
London, B. 204, vol. cxciv, 1901. 
8 Kershaw : A Fossil Solenostelic Fern. Ann. of Bot., vol. xxiv, 1910, p. 686. 
[Annals of Botany, Vol. XXV. No. XCIX. July, 19x1.] 
