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1907] CURRENT LITERATURE 73 
Water movement and turgor in wilting plants.—PrInGsHeErM has undertaken 
some important work which may be reasonably expected finally to bring us 
nearer an understanding of the movement of water in plants. The paper is 
quite long as compared with the experimental data, though this is perhaps justi- 
fied by the pioneer nature of the investigation.'' It seems to be quite universal 
in cases of wilting that the younger parts are favored in water supply at the 
expense of the older organs. Investigation proves that there is an actual passage 
of water from the basal to the apical portions, and that the latter transpire at a 
relatively greater rate. This movement is associated with a difference in osmotic 
potential between the base and the apex. The more rapid transpiration of the 
apical parts increases the concentration of the sap in that region, which is relieved 
xt a movement of water to that locality. This gradient of sap-density from 
to apex is correlated with a corresponding turgor gradient. Such facts 
aad the author to take issue with WresNER, who has regarded a movement of 
water as the determining factor in the emergence of adventitious organs. In 
such cases the author finds an increase in the concentration of the sap in those 
tissues from which the new parts emerge, which of course necessitates a move- 
ment of water in that direction. The difference of osmotic potential in a wilting 
shoot is, qualitatively, yep present and in no case did it appear where not 
initially present. ile the law of mass action undoubtedly operates to regulate 
the turgor, the author meee this an inadequate explanation for the relatively 
high constancy of turgor found.—RayMonp H. 
Growth and respiration during winter.—Srmon has studied what he calls 
the separate growth functions (shooting of buds, elongation of roots, callus- 
formation, secondary thickening, etc.) and respiration during the period of winter 
Test.‘? In some cases the suspended activity is autogenous, that is, not neces- 
sitated by external conditions. This is true of buds which rest only one season. 
Those which rest for several seasons do so because the external conditions are 
not suitable for their growth. If at any time during their long rest the proper 
conditions are supplied, growth activity is at once resumed. Such a period of 
inactivity is therefore called aitiogenous. The rest of a majority of the meris- 
tematic tissues is autogenous. The reduced elongation of the root is partially 
autogenous, but to a greater extent aitiogenous, while callus- formation is entirely 
the latter. Respiration does not show a period of rest corresponding to that of 
the growth functions. Under favorable conditions it may be relatively intense. 
If the temperature be raised to about 22° C. the intensity of respiration is found 
at any time during the rest period to be only about 25 per cent. less than at the 
time of its maximum, which is during the active season of the cambium. Res- 
™ PRINGSHEIM, ERNEST, Wasserbewegung und Turgorregulation in welkenden 
Pflanzen, Jays Wiss. Bot. 43:89-144. 190 
2 SIMON, SIEGFRIED, Untersuchungen ii aber das Verhalten einiger Wachstums- 
iiihcnen sowie der eo der Laubhélzer wahrend der Ruheperiode. 
Jahrb. Wiss. Bot. 4321-48. 
