Net H(+) influx inNitella clavata

Net H(+) influx measurements on the giant internodal cells of the alga,Nitella clavata, have been made by transferring the cells to solution of low pH, 4.5 to 4.7, and measuring the pH changes or the amount of acid addition required to maintain the low pH. The latter results are in very good agreement with those of Kitasato (1968) and thus support his hypothesis that theNitella membrane is very permeable to H(+). Other results indicate or suggest that the internal pH is changed only slightly under these conditions and that the membrane may have a rather large capacity to adsorb H(+) on the external surface.