156 PLANT RESPONSE 



to the short stationary period, it is to be borne in mind that 

 the death-point depends on the age of the tissue, and in the 

 tendril we have different parts in different stages of growth. 

 Hence while the uncurling movement of death was being 

 initiated in younger portions, older parts of the tendril were 

 still moving in an opposite direction. The outcome of these 

 antagonistic movements was a resultant pause, which only 

 lasted for a little while, and was followed by the vigorous 

 movement of uncurling, caused by the death-contraction of 

 the whole tissue. After the completion of the uncurling 

 movement, there followed the opposite, namely, the move- 

 ment of post viorteni relaxation. In a second experiment 

 with a younger specimen of tendril, I obtained results almost 

 identical. Here the uncurling response of death began at 

 one degree of temperature earlier, namely at 58° C, and the 

 index moved through 1 50 degrees of the circular scale. 



On the subject of the death-contraction of the radial 

 organs of ordinary plants, I shall speak in some detail in 

 the next chapter, and shall there describe the perfected 

 apparatus by which the thermo-mechanical response can be 

 continuously recorded, the curve exhibiting the death point 

 with great precision. 



{c) By observation of volumetric contraction, causing sudden 

 expulsion of water. — For the present I shall describe only 

 the third of those methods which I have enumerated for the 

 determination of the death-point, that namely which depends 

 on the sudden expulsion of water, at the moment of death, 

 from the hollow organ of an ordinary plant, previously filled 

 with liquid. The specimen used for the present demonstration 

 will be the peduncle of Allium, although there are many 

 tubular organs of various species of plants which are more 

 or less suitable for these experiments. 



We cut a length of about 10 cm. from the middle of a 

 peduncle of Allium, rejecting the too young and too old 

 portions at top and bottom. As the presence of air-bubbles 

 is likely to be disturbing to the experiment, the water used 

 must have been previously boiled. The specimen is placed in 



