EXPLANATION OF THE PLATES. 



MOHL ON THE PALM-STEM. 



PLATE I. 



FIGS. 1 8. Young leaves from the terminal bud of 

 Cocos flexuosa, in which the gradual production of the 

 pinnae is to be seen. The figures marked a represent 

 the leaflets of the natural size ; those marked b, the same 

 magnified. Originally (figs. 1, 2) a shallow furrow occurs 

 at the margin of the leaflet ; afterwards (figs. 3, 4) delicate 

 transverse striae appear at the bottom of the furrow; 

 these are converted (figs. 5 8) into slits, which penetrate 

 the substance of the leaf, and divide it into pinnae, as may 

 be seen in the cross section (fig. 7, c). The points of the 

 pinnae are connected by a cellular mass (fig. 8*), which 

 corresponds to the original margin of the leaf, and subse- 

 quently withers. 



Figs. 9 12. Young leaves of the bud of Phcenix 

 dactylifera, in which the pinnae originate, in like manner, 

 through slits which divide the simple leaf. 



NAGELI ON CELLS. 



PLATE II. 

 Figs. 1 3. Bryopsis Balbisiana Ag. 



1. Piece of an old tube; a and b, dead contents de- 

 tached from the wall, and beginning to dissolve ; c, living 

 contents which have become detached from the cell- 



