The ascent of sap to any point of plant causing there an increase of turgor in tissues is signalled by a deflection of galvanometric positivity. Two electric contacts are made on the stem. Knowing the distance
d from the root to the first lower contact A, and time-interval
t between the application of water and the first electric response, the velocity
v may be calculated by
v=
d/
t. If the ascendingwater then reaches the second upper contact a reversal of the previous electrical response may be caused. Taking this interval between two responses as
t', and the distance between the two contacts as
d', the velocity
v' of transport between the two points is given by
v'=
d'/t'The velocity calculated by the latter formula may be more accurate, because the distance from the root to the first contact cannot be determined as accurately as the distance between the two contacts.
Taking into consideration, moreover, of the results by the thermoelectric method it is concluded that the effect of probable variations in the absorption of water by roots are practically eliminated in case of the latter Di-phasic method.
The ascending velocities found by two experimental methods are shown in Table 1 and 2 respectively.
The present investigation was carried out in the Biological Institute of Tohoku University in Sendai during the summer in 1948 and 1949.
I wish to express my sincere thanks to the leader, Prof. Dr. Y. Yamaguti for the never failing interest he has taken in my work and his most valuable help and criticism.
View full abstract