PHENOMENA OF PLANT-LIFE. 91 



Large quantities of sap from specimens of Vitis aestivalis, Acer sacchar- 

 inum, Acer rubrum, Juglans nigra, Ostrya Virginica, and Betula 

 lutea, have been evaporated preparatory to making analyses of their min- 

 eral constituents. This work has not yet been accomplished, for lack of 

 time. 



EXPLANATION OP FIGURES. 



FIG. 1 represents two nodes of the squash vine. 



A is the petiole of a leaf showing vertical strise. 



B, a staminate flower on a long peduncle. 



C, a branching tendril exhibiting the mode of attachment to 



a support, and the double reversed spiral of the portion 

 between the support and the base of the tendril, by which 

 all the branches of a tendril are made to bear their share 

 of the strain, if they secure an attachment ; and by which 

 also great elasticity is given to the tendril, and the liabil- 

 ity of rupture largely diminished. 



D, nodal roots. 



E, a pistillate flower with a short peduncle. 



F, a lateral branch of the vine. 



G, a tendril Which, having failed in finding a support, has 



coiled upon itself and turned back towards the older por- 

 tion of the vine. 



FIG. 2 illustrates the structure of the tip of a squash rootlet, the cells of 

 the epidermis being often produced into root-hairs consisting 

 of single elongated cells, which increase immensely the absorb- 

 ing surface. 

 FIG. 3 shows a transverse section of a rootlet. 



A, epidermis with root-hairs. 



B, ordinary cellular tissue. 



C, a fibro-vascular bundle. 



D, loose parenchyma of the central portion of the rootlet. 

 FIG. 4 is a longitudinal section of rootlet. 



A, epidermis with root-hairs. 



B, cellular tissue. 



C, a dotted duct. 



FIG. 5 illustrates the structure of cork or periderm from a squash. The 

 cells are large, thin- walled, dry and brown. They are 

 developed in a radial manner from any highly vitalized cel- 

 lular tissue, when it is exposed to the air. Every place upon 

 the soft parts of a growing plant which is wounded soon 

 covers itself with this protecting layer of cork. 



FIG. 6 is a transverse section of a squash vine. 



A, the irregular internal cavity. 



B, fibre-vascular bundles. 



C, the outer green layer of the bark. 



