322 
the new shoots, and the tumescence of the lenticels below the 
diseased zone, indicated that here there was no lack of water, 
and that root pressure was operating in a perfectly normal way. 
On the other hand the rapid wilting and finally the complete 
desiccation of the tree commencing from immediately above the 
iseased zone, showed equally conclusively that the passage of 
this water up the stem was totally inhibited by some factor in 
the affected region. Yet in this zone itself the water-conducting 
elements were free from the presence of the fungus, whilst on 
the other hand the medullary rays and wood-parenchyma tissues 
were killed and occluded by the hyphae. 
These results seemed to lend strong support to the view that 
the living parenchymatous cells of the wood and medullary rays 
are fundamentally important and integral parts of the tissues 
concerned in the raising of water in the plant, a theory early 
i coulated by Westermaier* and Godlewski, t and more aaa | 
explanation has, however, been biked to very severe criticism. 
Strasburger|| for example in 1891 demonstrated that stems more 
than ten and a half metres hae continued to conduct water after 
they had been completely killed by steam, and similar experi- 
ments have been repeat y many observers since, which seem 
to prove indubitably that even when the vital activity of the cells 
purely physical forces rises in the stems of high trees. It is 
evident therefore that the inhibition, by death, of the vital func- 
tions of the living cells of the central cylinder in a zone ten or 
twelve centimetres in extent at the base of the specimen of 
Aesculus Pavia, could not be the primary cause of the wilting of 
the en AES & and the desiccation of the tissue 
* Westermaier, W. Zur Kenntniss der osmotischen Leistungen des 
— Parenchym’ s Ber. der —. bot. Gesell., Bd. i : 
odlewski, E. Znr Theorie der Wasserbewegung in den Pflanzen, 
AS saeabeer ics 3 ‘Wise Bot. hd v, 1884. fn 
t Urspru rage nach pak Beteiligung lebender Zellen am 
Seftateigen, ieretey Ze hae Centralb. Bd. 28, 191° , 
t of Water in Trees, Phil. Trans. Roy. Soe. - 
; Ewart, A. J. The Ascent 
Lond. vet 108s, 1905; and vol. 199x, 1908. 
; See Janse, J. M. Der Anfsteigende Strom in der Lge rende f. 
Mee Bd. 45, 1908; ii, Bd. 52, 1913, and fons ng, A., loc 
ra Se Webs b hnen 
Bi = Heine den Banu und Verriehtdnges der ‘siatadis aun 
