420 West.—On the Structure and Development of 
by the present writer typical lysigenous mucilage-ducts were found. But in 
the petiole of Angiopteris evecta an alternative schizo-lysigenous develop¬ 
ment of the mucilage-ducts was observed. The cells lining the cavity 
of these ducts develop as an indefinite transitory epithelium. Thus it 
seems that, as Farmer and Hill ( 1 . c., pp. 390-1) previously pointed out, the 
primitive method of mucilage-duct formation in this group of Ferns is 
Text-fig. 12. Text-fig. 13. 
Tannin-cells in ramenta of Danaea alata, Sm. x 280. 
Text-fig. 14. Tannin-cell in hair on petiole of Kaulfussia aesculifolia, Bl. x 280. 
lysigenous. The more advanced schizo-lysigenous method is restricted 
to the petiole of Angiopteris evecta . 
It is generally acknowledged that this genus is the most specialized 
member of the Marattiaceae, and hence it is not surprising that in this genus 
alone a more complex mode of mucilage-duct formation obtains. 
The form and position of the tannin-cells and tannin-ducts vary 
considerably even in different individuals of the same species, and afford no 
means of generic or specific distinction. 
Functions of the secretions. Although the mucilaginous secretions are 
produced in the youngest parts of the plants, they do not disappear from 
the older parts, and consequently are lost to the plant when the leaves and 
their appendages are thrown off or when the stem and roots decay away. 
It would thus appear that the mucilage constitutes a waste-product of 
the plant. The same explanation will serve for the tannin-sacs (and ducts), 
which also persist throughout the life of the plant organ in which they occur. 
