[VoL. 2 
784 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
the same work the author concludes the slime of the Fucaceae 
and of the Florideae to be of the ‘‘echter’’ type, occurring 
here, however, not as a layer laid down on the inner cell wall, 
but as an intercellular substance. Guignard (’93) held much 
the same view, and in an excellent histological investigation, 
clearly demonstrated the presence of slime or mucilage ducts 
in the Laminariaceae. 
Mucilages very similar in nature and origin to the algal 
slimes occur in the higher plants, and much more work has 
been done with them than with those occurring in the algae. 
It is hardly necessary to go into the historical aspect of this 
phase of the work. The current conception of its origin is 
voiced by Walliczek (’93), who, investigating rather fully the 
location of different types of normal mucilages by means of 
suitable stains, found that in almost all cases they were laid 
down as such. According to him, the slime forms secondary 
layers on the cell wall which he designates ‘‘ Membranverdic- 
kungsschichten’’—layers that in many instances almost com- 
pletely fill the cell. Where the epidermal layer of seeds be- 
comes gelatinous, as, for example, in those of flax, mistletoe, 
various Cruciferae, ete., it is this inner cell wall which Wal- 
liczek holds to be the seat of slime formation. Upon contact 
with water the slime swells remarkably, filling the cell and 
at times even bursting it. There may or may not be an actual 
hydrolysis of the true cellulose, but if there is it seems rarely 
to enter into mucilage formation. 
EXPERIMENTAL 
Forms used.—The algae to be used for enzyme investiga- 
tion were collected in the vicinity of Woods Hole, Massa- 
chusetts, during the summers of 1913-14, at which time the 
plants were also dried for winter work at the Missouri 
Botanical Garden. Work with the fresh tissue was carried 
on at the Marine Biological Laboratory, Woods Hole, during 
the latter summer. The selection of forms with which to work 
was limited to those relatively abundant in the neighboring 
waters, a further limiting factor in selection being relative 
freedom from adhering marine organisms. Only those plants 
