On the Structure and Development of the Secretory 
Tissues of the Marattiaceae. 
BY 
CYRIL WEST, B.Sc., F.L.S. 
With Plate XVIII and fourteen Figures in the Text. 
HE Marattiaceae are characterized by the possession of secretory 
JL tissues of two kinds, which have been called mucilage-canals, and also 
cells or ducts containing tannin. Owing to their prominence in this group 
of Ferns these tissues have received the attention of many botanists, the 
first reference to them appearing as early as 1847, when Karsten ( 11 ) 
observed mucilage-canals in the stem, leaves, and roots of the Marattiaceae 
and suggested that the cells bordering on these canals took part in the 
secretion of the mucilage. 
Harting ( 7 ) distinguished between the ramifying canals with a definite 
epithelium of small cells and the simple intercellular canals which he 
observed in a doubtful species of Angiopteris. 
Two kinds of mucilage-canal were also described and figured by 
Frank ( 10 ), who contrasts those which occur in the outer thick-walled tissue 
of the petiole of Angiopteris with those which are found in the inner 
thin-walled tissue. To the former he ascribes a lysigenous origin, but to 
the latter, which are wide-lumened and are lined with an epithelium of small 
iso-diametric cells, he attributes a schizogenous origin. 
As a result of his investigations on species of Angiopteris and of 
Marattia , Trecul ( 21 ) arrived at a very similar conclusion, but maintains 
that the secretory elements in the fibrous zone of the petiole consist of 
a series of superposed large elongated cells containing tannin, while the true 
mucilage-ducts, although they arise schizogenously, possess only a transitory 
epithelium. 
Van Tieghem ( 20 ) found both mucilage-ducts and tannin-sacs in 
the root and petiole of Marattia laevis. According to this author the 
former (mucilage-ducts) are lined with an indefinite epithelium of small 
irregular cells, from which the mucilage is derived. He adds, however, that 
here and there the ordinary large cells of the cortex abut directly upon the 
canal. In the root of Angiopteris evecta no mucilage-canals were found. 
[Annals of Botany, Vol. XXIX. No. CXV. July, 1915.] 
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