1906] CURRENT LITERATURE 153 
atmospheres, with a total resistance to flow in the trunk of 1o-12A. ‘“‘It appears, 
therefore,” concludes Ewart, “that to maintain flow, a pumping action of some 
kind or other must be exercised in the wood, for which the presence of active 
living cells is essential... . . There is no known means by which these cells 
can directly pump water in a definite direction. . .. . It is suggested that the 
wood parenchyma cells, by the excretion and reabsorption of dissolved materials, 
may bring into play surface tension forces within the vessels of sufficient aggre- 
gate intensity to maintain a steady upward flow, and to keep the water of the 
Jamin’s chains in the vessel in a mobile condition, ready to flow to wherever 
Suction is exercised.” 
But STEINBRINCK declares himself (J. c.) unable to form any conception of 
how such an action can be produced, and LARMOR objects'+ on purely mechani- 
cal grounds, saying: “If the osmotic gradient, assisted by capillary pull at the 
leaf orifices, is insufficient to direct a current of transpiration upward, capillary 
alterations inside the vessels, arising from vitally controlled emission and absorp- 
tion of material from the walls cannot be invoked to assist.” He suggests that 
osmotic changes in the vessels, of peristaltic character, might do; but he appar- 
ently does not know that osmotic phenomena do not occur in sap vessels. As 
a physicist, he inquires whether there is a sufficient stock of energy in the stems 
for the pumping work required; and he renews the eminently plausible suggestion 
that the work is done where the external energy is received, viz., in the leaves. 
It cannot be said that these researches have solved the problem of water 
Movement. But each in its own way has added something to our knowledge. 
The more hopeful lines seem to be in determining physical factors and studying - 
more closely the dynamics of the question.—C. R. B. 
Gymnosporangium galls.—The anatomical changes induced by Gymno- 
Sporangium clavariaeforme and G. juniperinum on the twigs and teaves of their 
host, Juniperus communis, have been investigated by L RE'S with the 
following main results. The mycelium of G. clavariaeforme inhabits the cortex 
and phloem regions, but does not penetrate into the wood. The cells of the 
Cortex are multiplied and enlarged so that all lacunae. are obliterated, resulting 
'n @ general hypertrophy of this region. The formation of collenchymatous 
Ussue is almost entirely suppressed. In the phloem region the medullary rays 
undergo the most marked transformation. Not only do the rays themselves 
become More numerous, but the cells composing them are also greatly increased 
'n number, so that this tissue is likely to make up about one-half the volume of 
the bast region. The sieve tubes, parenchyma, and bast fibers retain their 
"normal succession, but owing to the great increase in parenchyma from the rays 
and from the increased volume of the bast parenchyma, the course of the sieve 
BRR pee 
‘ “4 Larmor, J., Note on the mechanics of the ascent of sap in trees. Proc. Roy. 
Soc. B. 76: 460-3. 1905. 
*S LAMARLIERE, L. GENEAU DE, Sur les mycocécidies des Gymnosporangium. 
Sc. Nat. Bot. IX, 2:313-350. pls. 8-12. 1905. 
Ann. 
