HARVARD UNIVERSITY 
CamprinGk, Massacnuuserrs, AuGust 2, 1940 Voi. 8, No. 9 
THE FORMATION OF SEPTA IN THE 
FIBER-TRACHEIDS OF 
Hypericum Androsaemum 1a. 
BY 
Pau A. VestanL AND Mary R. Vesta 
ALTHOUGH the presence of nuclei in fibers has been 
established (9, p. 56), the work of Bailey (6), Goldstein 
(12), Wareham (16), and Esau (10) suggests that the 
apparent occurrence of the multinucleate condition in 
fibers is due to a misinterpretation of the material, ex- 
cept in the phloem. As far as we are aware, no descrip- 
tion has been given of a division of the protoplast in a 
fully developed cell to form a nucleated septate fiber- 
tracheid. 
The definition of a septate fiber-tracheid, now widely 
accepted, is ‘‘A fiber-tracheid with thin, transverse walls 
across the lumen. (In these elements the protoplast di- 
vides after the formation of the secondary wall. The 
septa are true walls)’’ (8). This definition recognizes the 
septate fiber-tracheid as a distinet modification of the 
fiber-tracheid, which in turn is transitional between a 
tracheid and a libriform fiber. The presence of nuclei 
during the early stages of maturation is assumed but not 
stated. 
In an earlier paper (15) it was reported that the fiber- 
tracheids present in the secondary wood of the genus 
Hypericum are septate or non-septate and typically con- 
tain a nucleus. Occasionally the nucleus was seen in 
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