A Study of the Enzyme-secreting Cells in the Seedlings 
of Zea Mais and Phoenix dactylifera 1 . 
BY 
HOWARD S. REED, 
Instructor in Botany in the University of Missouri . 
With Plate XX. 
I. Historical. 
T HE morphology and physiology of secreting-cells offer an inviting 
field for study. Their metabolism is more active and continues for 
a longer time than that of embryonic tissue. The constant removal of 
the products of synthetic activity affords opportunity for observing the 
changes which accompany their production. Some of the most instructive 
descriptions of these cells have been given by students of animal histology, 
the highly specialized glands of animals affording a favourable subject 
for investigation. A brief resum^ of the most important contributions 
to our knowledge of the subject is here given. 
Charles Darwin (75) described the changes occurring in the stimulated 
gland-cells of Drosera rotundifolia during the process of digestion. His 
experiments were carried farther by his son, Francis Darwin (76, 77, 78), 
using Drosera rotundifolia and Dipsacus fullonum. Following their work 
came that of Schimper (’82) on Sarracenia, Drosera , and U tricularia ; 
Fromann ( 5 84) on the glandular hairs of Pelargonium ; and de Fries (’86) 
on Drosera. The first detailed cytological study of secreting-cells in 
plants was that of Gardiner (’85) on the gland-cells in the tentacles of 
Drosera dichotoma. He saw that the process of secretion was accompanied 
by vacuolization and destruction of the cytoplasm in the distal end of the 
cell, but the nucleus was always surrounded by a dense layer of proto- 
plasm. His explanation of the process of secretion was that the cytoplasm 
contains a ‘ formed substance 5 derived from the protoplasm, and that the 
out-pouring of the secretion is caused by the repeated breaking down of 
the protoplasm into this 4 formed substance,’ which is of a mucous nature 
and, attracting water, escapes as the secretion to the external surface. 
1 LXX. Contribution from the Botanical Laboratory of the University of Michigan. 
[Annals of Botany, Vol. XVIII. No. LXX. April, 1904.] 
