242 BOTANICAL GAZETTE [SEPTEMBER 
various hydrogen ion concentrations, or in solutions contain- 
ing Ca, Mg, Mn, oxalate, or SO, ions (cf. also MasING 31 and 
LOEB 28). 
OvERTON (49) made successive determinations of the weight 
of sartorius muscles of the frog during treatment with various 
solutions. He reports that no increase in weight took place in a 
0.7 per cent sodium chloride solution during a period of many hours; 
that isotonic solutions of the phosphate, tartrate, sulphate, ethyl 
sulphate, and acetate of potassium induced no change in weight 
during 50 hours. After a few hours an increase of weight occurred 
in solutions of potassium chloride, iodide, bromide, and nitrate, 
but OvERTON found these changes to be irreversible, and concludes 
that the normal muscle is impermeable to neutral salts. STEBECK 
(57), on the other hand, finds that under proper conditions the 
increase in weight of kidney tissue in a pure isotonic solution of 
potassium chloride is reversible, and therefore considers that these 
cells are normally permeable to potassium chloride. In general 
the permeability of animal cells to neutral salts seems to be less, and 
- more often characterized by selective peculiarities than that of 
plant cells. The red-blood corpuscles, for example, may well be 
considered to be surrounded by a considerably specialized proto- 
plasmic envelope. 
The experiments of Lor (29) on the permeability of fertilized 
_Fundulus eggs to electrolytes are concerned with a peculiarly 
specialized envelope surrounding the embryo. This envelope is” 
characterized by an exceedingly small permeability to salts. Thus — 
an embryo 4-14 days old within the egg membrane survives 3 days 
of exposure to a solution (so cc. 3 M NaCl+x cc. 10/8 M CaCl.) 
which is almost instantly fatal to the newly hatched fish. As has 
previously been noted, generalizations as to the permeability of 
_ protoplasm cannot be made from data furnished by experiments — 
on such a membrane, and a more extended discussion of the results , 
of these experiments would not be profitable pete : 
- Electrical I conductivity « of tissues or of masses 5 of cals 
