[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, etc., 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 



