1904] CURRENT LITERATURE 157 
of different types expressed in terms of physiography and taxonomy, the history 
and dynamics of each being reserved for later treatment. A somewhat detailed 
account is given of Nyssa uniflora, special attention being called to the very much 
enlarged base, an enlargement which does not become conspicuous where the 
water supply is scanty; and of Taxodium distichum with its enlarged base and 
“knees,” neither of which phenomena appears in connection with dry soil. The 
half-tone reproductions of good photographs are excellent and form a substantial 
addition to the data presented by the paper.— a 
REGENERATION.—WINKLER’S *9 Senrees on Torenia show that detached 
leaves of this plant may produce buds from any part of the upper epidermis. 
The shoots proceeding from these buds bloom at once, independent of the age 
of the parent plant and of the place on the plant from which the leaf is taken. 
The term “regeneration” should be confined to cases such as this, where fully 
differentiated cells resume the embryonal state—S1mon°° has studied the exact 
region of regeneration in root tips, and determined by microscopic observation 
and by experiment that the pericambium is essential. He distinguishes direct 
regeneration or replacement of the tip from partial regeneration, where the peri- 
cambium grows out from the cut surface in the form of a ring and the new tissue 
eventually spreads over the whole cut surface. The latter variety of regeneration 
occurs when more than about 0.75™™ of the root tip is cut off; if 1-3"™ is cut 
off, no regeneration takes place, but lateral roots replace the primary root. Three 
periods of regeneration are distinguished: (1) reaction, time occupying about 
one day, (2) introductory phase, consisting in pericambial division, (3) definite 
formation of the new tissue—V6cHTING?! calls attention to the marked lack of 
plasticity in Araucaria excelsa. The bilateral branches of the first order when 
used as cuttings produce a plant which retains the bilateral habit; branches of 
the second order root slowly and grow in length without branching; only the tip 
of the main axis gives a plant of the regular radial habit. As to the nature of 
regeneration in general, the writer holds that the capacity to regenerate, though 
hot always of use either to the individual plant or to the species, is as character- 
istic a phenomenon as is growth—M. A. CHRYSLER. 
THE MODE in which light affects perceptive organs is awakening interest. 
In his paper summarized on p. 154, HABERLANDT suggests that perhaps light is 
perceived by reason of the difference in pressure between illuminated and dark 
watsraelliha c same suggestion is made by Jost,3? but neither mentions RaD1,*? 
asiatica. Ber. De are Bot 
‘i 3° Smuon, S., SPELT a iiber die PRAT der Wirzelspitze. Jahrb. 
Iss. Bot. 40: sa 1904. 
Bo *' VécutINc, H., Ueber die Regeneration der Araucaria excelsa. Jahrb. Wiss. 
t. 40: sie as 1904. 
0 WINKLER, H., Ueber — Lancs auf den Blattern von Torenia 
sells. 107. 1903 
* Vorlesungen"iiber Pflanzenphysiologie 586. Jena. 1904. 
33 Unters. iiber den Phototropismus der Tiere. Leipzig. 1903. 
