West. — A Contribution to the Study of the Marattiaceae . 403 
2. Mucilage Canals , Tannin Cells, and Tannin Ducts. 
A comparative account of the structure and development of the 
various secretory tissues found in the Marattiaceae was published by the 
present writer (68) in a recent number 
of this journal, to which the reader 
is referred. Since the publication of 
that paper, however, the writer has 
observed in a moderately large root 
of Marattia Ccoperi a mucilage canal 
traversing the endodermis (Text-fig. 32). 
When it is remembered that in the 
roots of this plant the mucilage canals 
arise very early just behind the growing 
point, it becomes apparent that, apart 
from the cells of the ground tissue, 
others, which would normally become 
endodermal cells, may be concerned 
in the formation of the canal. More- 
over, stelar tissues in the strict sense also 
take part in the formation of the canal. 
3. Secondary Thickening . 
No trace of secondary thickening, such as that described and figured 
for Angiopteris and for Marattia by Farmer and Hill ( 29 , p. 388, PI. XVIII, 
Figs. 26, 28), was observed in the stem of either species of Danaea examined 
by the present writer ; neither was it found in the rhizome of Kaulfussia 
aesctdifolia ; but regular tangential division of the pericyclic parenchyma 
was noticed in old roots of Marattia Cooperi , Mre. The cells which 
exhibit this secondary activity appear to be sister cells of the endodermis 
(cf. Farmer and Hill, 29 , p. 388). 
4. Mycorrhiza. 
The Fungi which are normally associated with the roots of this group 
of Ferns have recently been described by the writer (69 and 70 ). Further 
reference to the mycorrhiza of the Marattiaceae is therefore unnecessary. 
5. Cavity P arenchynia (— Tyloses ). 
Cavity parenchyma was frequently met with in both species of Danaea 
examined. Series of intrusive thin-walled cells of the ground -tissue, 
similar in appearance to those described by Brebner ( 12 , p. 544, PL XXIII, 
Fig. 22) for Danaea simplicifolia , and by McNichol ( 48 , p. 408, PL XXV, 
Text- fig. 32. Marattia Cooperi , Mre. 
Transverse section of a root showing a 
mucilage canal {m.c.) traversing the endo- 
dermis ( e .). c., cortex ; r.h., root-hair; xj/., 
xylem. x 30. 
