of Vascular Strands in Angiopteris evecta . 373 
plete, a circumstance partly perhaps to be ascribed to the 
small amount of material at his disposal. 
The next paper of importance is the often quoted memoir 
of Mettenius (1864) 1 , who in a magnificent monograph really 
laid the foundations of our knowledge of the intricate dis- 
tribution of the vascular strands. His specimen, as is well 
known, was a mature plant which was in a moribund condi- 
tion when he investigated it, a fact which probably accounts 
for some of the anomalous characters met with near the apex. 
He clearly distinguished the concentric funnel-shaped zones 
of vascular strands which form so characteristic a feature in 
the bulky stems of these plants, and he corrected the mistake 
of De Vriese and Harting of not distinguishing the intra- 
cortical roots from the foliar strands. The leaf-trace bundles 
were shown to form the upward and outward continuation 
of the funnel-shaped lattice work, and he grasped the character 
of the anastomoses, whereby the exit of the traces was com- 
pensated for by branches from the next internal zone of 
vascular strands. The details observed by him in this con- 
nexion will be discussed later on in relation to the arrange- 
ments met with in the younger sporophyte. Mettenius’s 
account is confirmed in all important details by Miss Shove 2 3 , 
who failed, however, to identify in her specimens the middle 
leaf-trace steles stated by Mettenius to originate from the 
next inner zone of bundles. This discrepancy may perhaps 
be explained as due to a difference in the stage of develop- 
ment of the plants in the two cases. Our own observations 
show that in young plants only the two stout lateral steles 
pass out to the petioles, all the rest being as yet in abeyance. 
In 1889 a paper by Kuhn appeared in ‘Flora,’ and dealt 
with 1 the arrangement of the vascular strands in younger 
plants of Marattia and Angiopteris , as well as of Kaulfussia. 
1 G. Mettenius, Uber d. Bau von Angiopteris , Abh. d. k. s. Ges. d. Wiss., ix. 
2 R. F. Shove, on the structure of the stem of Angiopteris evecta. Annals 
of Botany, xiv. 
3 V. R. Kiihn, Untersuchungen u. d. Anatomie der Marattiaceen u. Gefass- 
kryptogamen. Flora, Bd. lxxii, 1889. 
