230 



PHYSIOLOGY OF NUTRITION. 



somewhat eagerly sucks up water poured into the tube. The sap 

 only gradually begins to flow. 



1 Dutrochet, Memoires pour servir a Vhistoire anatoinique et physiologique de 

 vegetaux, 1837, p. 193. 



2 See Wieler, Jahrbilcher f. wissenschl. Botanik, Bd. 19. 



3 See Strasburger, Ban und Verrichtung der Leituiigsbahnen, Jena, 1891, pp. 

 519 and 569. 



4 See Elfving, Botan. Zeitung, 1882, p. 714 ; Vesque, Ann. d. sc. nat. Bot., 

 VI. Ser., T. XIX., p. 188 ; Scheit, Botan. Zeitung, 1884, p. 201 ; Errera, Comptes 

 rend, de la soc. roy. de. bot. de Belgique, T. XXV., II. Th., p. 28 ; Strasburger, 

 Bau und Verrichtung der Leititngshahnen, Jena, 1891, p. 541. 



5 See Errera, Berichte d. Deutschen botan. Gesellschaft, Bd. 4, p. 16. 



6 Literature respecting the movement of water : Sachs, Lectures on the 

 Physiology of Plants ; Hartig, Gasdrucktheorie, 1883 ; Westermeyer, Berichte 

 d. Deutschen botan. Gesellschaft, 1883 ; Godlewski, Jahrbilcher f. wusenscld. 

 Botanik, Bd. 15 ; Scheit, Jenaische Zeitschrift f. Natunvissenschaft, N.F. Bd. 

 12 ; Strasburgar, Bau und Verrichtung der Leitungsbahnen in d*n Pflanzen, Jenn, 

 1891; Schwendener, Sitzungsberichte d. Akadem. d. Wiss. zu Berlin, 1892. 



7 See Detmer, Beitrdge zur Theorie d. Wurzeldrucks, in Preyer's Physiolo- 

 gische Abhandlungen, 1877, Bd. 1, Heft 8, p. 37. 



85. The Mobility of the Water in the Wood. 



We cut from a trunk or bough 

 of Abies pectinata, 2-4 cm. in 

 diameter, a piece 15-30 cm. in 

 length. It must be very rich in 

 water, and therefore it is best to 

 take it in winter from a living 

 plant, and possibly place it in 

 water for some time before the ex- 

 periment. The carefully smoothed 

 cut surfaces of the wood appear 

 dry. If, however, holding the 

 object vertically, we place a thin 

 layer of water on its upper sur- 

 face with a paint brush, we may 

 observe that this water rapidly 

 sinks into the wood, while the 

 lower cut surface becomes moist. 

 Rapidly turning the piece of wood 

 upside down, a repetition of the 

 process is to be observed. A 

 FIG. 87. Apparatus for demonstrat- minimal pressure is therefore 



ing the readiness with which water 



moves in the wood. sufficient to set in motion the 



