574 
BOTANY: S. C. BROOKS 
It will be seen that these observations are in accord with those made 
by other methods; and in addition it shows the advantage of a balanced 
solution over saccharose (which is often used on the assumption that it 
does not penetrate nor alter the permeability of protoplasm) in experi- 
ments in which it is desirable to maintain the normal permeabihty of 
living cells. 
^'z^wwar^'.— Determinations of permeability have been made by a 
new method, which is independent of other methods, as well as by 
improved forms of existing methods. 
FIG. 5. THE RATE OF PENETRATION OF SALTS IN PURE AND BALANCED SOLUTION INTO 
LIVING CELLS OF TARAXACUM. 
FIG. 6. THE RATE OF PENETRATION OF SACCHAROSE AND OF SALTS IN PURE SOLUTION 
INTO LIVING CELLS OF TARAXACUM. 
The results agree in showing: 
(1) That living protoplasm is normally permeable to the salts studied. 
(2) That salts in pure solution may alter permeability, some (like 
sodium chloride) causing an increase of permeability while others (like 
calcium, lanthanum and cerium chlorides) cause a decrease, followed 
by an increase, of permeability. 
(3) In a properly balanced solution the permeabiht remains normal. 
(4) Cell walls may be semipermeable to an extent which renders 
them important in such experiments. 
FIG. 5. 
FIG. 6. 
