450 ON THE MUCILAGE-CANALS OF THE MARATTIACES. 
finds that all such structures, in the thirteen families examined by 
her, are typically schizogenous in origin. She sums up her results 
as follows:—‘‘ Nous pouvons done dire que dans tous les cas 
étudiés les canaux sécréteurs et les poches sécrétrices se consti- 
tuent par écartement de cellules et jamais par destruction de 
tissu. Le mode de formation de ces organes est schizogéne et 
non lysigéne” *. The typical schizogenous development of the 
mucilage-canals of the Marattiaceze would bring another important 
group into agreement with v. Tieghem and Mlle. Leblois’ views, 
but for the peculiar canals in the roots of Angiopteris evecta 
var. pruinosa and var. Teysmaniana, in which the origin is 
schizogenous, but not typical, as subsequently lysigenesis takes 
place. Tschirsch favours a schizogenous origin with a lysige- 
nous development in certain cases, and other careful observers 
previously found certain of these structures to be lysigenous 
which Mile. Leblois considers schizogenous. Only exhaustive 
examination of every doubtful case by the aid of the most refined 
modern methods will afford a true basis for generalization, and 
that has yet to come. 
Summary. 
Typical mucilage-canals occur in the Marattiacezx, 7. e. schizo- 
genous intercellular spaces with a living secretory epithelium. 
This was actually demonstrated in the fronds of A. evecta, 
Marattia alata and M. cicutefolia. They are in every essential 
feature similar in mode of origin and development to the well- 
known resin-canals of Hedera, Pinus, &c., and are not produced 
by the mucilaginous degradation and death of cells. 
No mucilage-canals were found in the roots of A. evecta and 
A. evecta var. hypoleuca ?, but rows of tannin-sacs which simulated 
canals. 
In the aerial roots of A. evecta, var. pruinosa and var. Teys- 
maniana, a ring of peculiar mucilage-cavities was found in the 
cortex; these cavities have no secretory epithelium, and seem to 
have a schizo-lysigenous mode of origin. 
True mucilage-canals were found in the roots of Marattia 
attenuata, in which the only variation from the commoner mode 
of development was the want of definiteness in the earliest stages 
of the initial group and the very frequent irregularity in the 
development of the split. 
* In Ann. Sc. Nat, 7° sér. Bot. v., vi. (1887), p. 315. 
