304 
Del/. — Studies of Protoplasmic Permeability by 
Comparison of the Two Plants. 
Although the two types of material selected are not physiologically or 
morphologically very similar, their general behaviour in relation to 
temperature is obviously in agreement. In Figs. 12 and 1 5 the two curves 
have the same general relations. On closer comparison it will be seen that 
Fig. 15. Curve of relation to temperature of the rate of shrinkage of tissue of dandelion scape. 
Interpretation as in Fig. 12 (p. 299). 
for temperatures of 25 0 C. and upwards the values of the relative per- 
meability are practically identical, while below 25 0 the dandelion values 
decline faster than those of the onion. It cannot yet be said whether this 
is related to the fact that the dandelion is a summer plant, the experiments 
being done in April to June, while the onion leaves had lived through the 
winter and were investigated from January to March. 
The agreement and divergence between the two plants is best brought 
