544 JACQUES LOEB AND HARDOLPH WASTENEYS 
of pigment and trimethylamin had become as good as that in 
the cultures kept at 22°. The organisms had, therefore, become 
‘adapted’ to a temperature of 35° which at first was unfavorable. 
Dieudonné did not succeed in causing pigment formation in 
this bacillus at a higher temperature than 35° although the bacil- 
lus finally grew at a temperature of 41°.5. He obtained similar 
results in experiments on other pigment-forming bacteria. Daven- 
port and Castle? made experiments with tadpoles of frogs. One 
lot of eggs and tadpoles was kept at about 15°, a second lot for 
twenty-eight days at 25°C. While the tadpoles raised and kept 
at 15° went into heat rigor at 40°.3C., those kept for twenty-eight 
days at 25° were not affected by this temperature but went into 
heat rigor at 48°.5. Their resistance to high temperature had 
therefore risen 3°.2. When the latter tadpoles were put back for 
seventeen days to a temperature of 15° they had lost their resist- 
ance to high temperature to some extent but not completely, 
since they went into heat rigor at 41°.6. The authors suggest 
that this adaptation to a higher temperature is due to a loss of 
water on the part of the protoplasm. They assume that the rise 
in temperature causes a comparative acceleration in the excretion 
of water on the part of the tadpoles. The hypothesis of these 
authors is based upon the fact, that spores of bacteria are more 
resistant to high temperatures than the bacteria. While this is 
a fact, nothing in the experiments of Davenport and Castle proves 
that the amount of water in the tadpoles is diminished by the rise 
in temperature. The idea of Davenport and Castle was put to 
a direct test by Kryz.? He kept frogs, toads and salamanders 
at room temperature, and at temperatures as high as 40°C., for 
a number of days or weeks and tested the coagulation temperature 
of the muscle plasma for both ranges of temperatures. He found 
that the coagulation temperature was identical for the animals 
kept at low and those kept at high temperatures. 
The following observations by Kammerer’ indicate also an after- 
effect of the raising of temperature. Lacerta muralis from the 
2 Davenport and Castle, Arch. f. Entwickelungsmechanik, vol. 2, p. 227, 1896. 
’ Kryz, Arch. f. Entwickelungsmechanik, vol. 23, p. 560, 1907. 
* Kammerer, Arch. f. Entwickelungsmechanik, vol. 30, p. 379, 1910. 
