1897 | CURRENT LITERATURE . 481 
The regeneration of the periderm is not prevented by the checking of 
secondary thickening. In the open twigs from which the periderm was sliced 
replaced it from the cortical parenchyma, though the number of cells was not 
so great as the normal, except in Saméucus nigra in which they were more 
numerous. In a moist atmosphere the exposed cortical cells grew into long 
tubes, forming a callus, from which the periderm was produced. 
No regeneration of epidermis was observed, but its removal was followed 
by the formation of cork or of callus and then cork. 
Wax coverings were replaced in only three plants observed, Ricinus com- 
munis, Rubus biflorus, and Macleya cordata, and then only when the plants 
were still in vigorous growth. Several sedums and echeverias examined 
did not secrete wax after it had been removed. Light produced no effect 
upon this process, and moist air diminished, but did not entirely prevent it. 
The removal of the cuticle could only be accomplished upon leaves with 
avery thick outer epidermal wall, such as the agaves and aloes possess. 
When sliced off it was reformed, even in the moist air, in which, however, it 
was thinner. Filaments of Cladophora glomerata were cut into pieces (which 
do not grow longer) and cultivated for four weeks. ‘The transverse walls, 
how exposed, became covered with a cuticle. Typical water plants, like 
Ceratophyllum demersum and Elodea Canadensis, could not thicken the cuti- 
cle on exposure to air, so that it was impossible to cultivate them under new 
conditions. Even the submersed leaves of ANuphar luteum and N. advena 
could not live as floating leaves. On the contrary the water leaves of Sagit- 
 taria sagittif~olia and Hippuris vulgaris, upon exposure to air, lived and thick- 
ened the cuticle strongly. Some land plants (Afentha aquatica, Polygonum 
Hydropiper and Lysitmachia nummutaria) easily adapted themselves to a 
_ submersed life, forming then es a = cuticle as a result of dimin- 
ished transpiration. 
The delicate membrane covering the cells setie upon the large inter- 
cellular spaces of many water plants (and some land plants also), designated | 
as — oe , reacts om ee transpiration, becateing partly lifted poe 
up fro _ Whatever its 
rei is eerily not evant to the true cuticle —C. R B. 
