72 
Birbal Sahni. 
THE VASCULAR ANATOMY OP THE TUBERS 
OF NEPHROLEPIS. 
By Birbal Sahni, 
Emmanuel College, Cambridge. 
[With Three Figures in the Text]. 
Introductory. 
LTHOUGH from the point of view of their biological signifi- 
cance the tubers borne on the underground stolons of 
Nephrolepis have been the subject of frequent comment 1 , their 
vascular anatomy does not appear to have received the attention it 
deserves. The investigations of Professor Heinricher, who studied 
the tubers under artificial conditions of culture, while dealing in a 
most interesting manner with the biological problems, leave the 
vascular anatomy out of consideration, and since 1889 no reference 
has been made to it. In that year Lachmann 2 made the observation 
that the single strand traversing the stolon breaks up at the base 
of the tuber into a number of smaller strands usually concentric or 
rarely bicollateral in structure, which form a network lying in the 
peripheral part of the tuber, parallel to its surface, and converge 
again towards the apex of the tuber, there uniting into a single 
strand. Lachmann, however, did not describe the changes which 
the strand undergoes in order to give rise to the reticulate system 
traversing the periphery of the tuber; and as these form an 
interesting parallel to the mode of elaboration of the dictyostele 
from the protostele in the ontogeny of many Ferns, they would 
seem to be worthy of description. 
The material for this work consisted partly of tubers of 
Nephrolepis cordifolia from the Cambridge Botany School, and 
partly of fresh tubers of the same species obtained from the 
Cambridge Botanic Garden through the kindness of the Curator, 
Mr. R. Irwin Lynch, M.A., to whom I wish to express my hearty 
thanks. 
» y 
1 Sperlich, A., Flora, 1906, p. 451 ; Sperlich, Flora, 1908, p. 341 ; Hein¬ 
richer, E., Flora, 1907, p. 43. 
a Lachmann, J.-P., “Contributions k, l’histoire naturelle de la racine des 
fougeres,” Lyon, 1889, These presentee il la faculte des sciences de Paris, 
pp. 155-6 ; Hofmeister, W., “ Beitrage,” etc., II. Abhandl. d. kgl. sachs. 
Ges. d. Wiss. V. Math.-Phys. Klasse III., Leipzig, 1857, p. 651. 
Beyond the remarks contained in these two communications I am not 
aware of any reference hitherto made to the subject in question. 
