388 BOTANICAL GAZETTE [OCTOBER 
Breton Island, appending various explanatory remarks which should prove 
useful to students attempting to make similar applications to other regions.— 
Gro. D. FULLER 
Permeability——Several interesting contributions to our knowledge of 
protoplasmic permeability have appeared recently. DEt¥F has investigated 
the influence of temperature on the permeability of protoplasm to water by the 
tissue shrinkage method, using sections of onion leaves and dandelion scapes 
in subtonic solutions of cane sugar. The curve of contraction at different 
temperatures was measured by means of an optical lever which greatly mag- 
nified the shrinkage, and from this curve the rate of contraction. at the 
time when 30, 50, and 70 per cent of the shrinkage had occurred, was measured 
by the tangents to the curves at these points. From the rates the values for 
Q:. were obtained. This value increases as the icmperetur rises. In the 
onion leaf the value of Q® at 10-20° C. is 1.5, at 20-30° C. is 2.6, and at 30- 
40° C. is 3. o. In the dandelion scape the greatest value of Q,. was obtained 
at 20-30°C., at which temperatures it was 3.8. Above and below those 
temperatures the value falls. Contrary to the results of VAN RYSSELBERGHE, 
who found very little increase in permeability above 20° C., DEtF finds that 
permeability of the protoplasm to water continues to increase rapidly up to the 
highest temperature investigated, 42°C. The methods used by VAN RYSSEL- 
BERGHE are justly criticized, particularly with reference to the means of deriving 
a temperature relation from his data. The strength of solutions used by VAN 
RYSSELBERGHE may also have led to serious errors. 
Miss Hinp* has studied the absorption of acids by living plant tissues, 
using electrical conductivity methods, and electrometrical measurement of 
the cate ion concentration in acid solutions which were in contact with living 
potato disks and roots of Vicia Faba. She found that the hydrogen ion is 
aR absorbed from dilute acid solutions by living tissues, and concluded 
that the anion, particularly in organic acids, plays a large part in determining 
the effects of the acid on protoplasm. In the case of the mineral acids, HCl, 
HNO,, and H.SO,, the stronger solutions can penetrate the cells for a time 
without causing much injury as measured by exudation of electrolytes; but 
organic acids like formic and acetic cause very rapid increase in conductivity, 
due to exosmosis of electrolytes from the cell. With these two acids there is 
first a decrease and then after a few hours a very noticeable increase in’ H+ ion 
concentratién. This is thought to be due possibly to the production of acids 
within the tissues which diffuse out through the altered plasmatic membrane. 
- , E. Marion, Studies of protoplasmic permeability by measurement of 
rate of i. of turgid tissues. I. The influence of temperature on the per- 
meability of protoplasm to water. Ann. Botany 30:283-310. 1916. 
s Hinp, Mitprep, Studies in permeability. III. The absorption of acids by 
plant tissue. Ann. Botany 30:223-238. 1916. 
