48 THE EVOLUTION OF LIFE 
together with Water Fleas, were found to be killed 
at or about 110° F. 
Experiments were also made with the seeds of 
the Chick-pea, Lentil, Wheat-grass, Flax and 
Clover. The mode of procedure was as before, so 
that there was only a momentary exposure to the 
temperatures about to be cited. Of those which 
had been exposed to 190° F. many did not 
germinate ; still fewer of the seeds that had been 
exposed to 201° produced young plants; while of 
those heated to 212° not one germinated. After 
the young plants which had been developed from 
seeds heated to lower temperatures had grown for 
thirteen days their capability of resisting heat was 
tested in the manner described (that is, by only 
immersing the roots of the plants in water, while 
the temperature was being raised), and with the 
following results. Those whose roots had been 
momentarily exposed to 156° continued to live 
after they had been replanted ; while others whose 
roots had been exposed to 167° and upwards 
speedily dried up and perished, though all alike had 
been carefully replanted in well-watered earth. 
Spallanzani’s method here was defective. The 
whole of the plant, in each case, ought to have been 
immersed in the water; and had this been done 
they would probably have succumbed at very 
much lower temperatures, as Sachs has_ since 
shown. } 
This investigator says,! ‘I have convinced 
myself that a considerable number of plants are 
1 “ Text-Book of Botany,” transln., 1875, p. 650. 

