178 PLANT RESPONSE 



modified in contrast with the normal curve. The most 

 striking difference lay in the lowering of the death point by 

 3°C. ' 



Comparison-Morograph. — In order to facilitate the 

 investigation into the modification of the curve, by various 

 agents, I have devised a Comparison-M orography by means of 

 which the thermo-mechanical curves of two similar speci- 

 mens, one under normal and the other under modified con- 

 ditions, can be taken simultaneously. We use here two 

 recording Optic Levers, supported on a single thermometric 

 helix. The normal specimen is placed in the internal 

 cylinder in the ordinary way and attached to one of the 

 Optic Levers. The second specimen, contained in a small 

 cylindrical tube, filled with the given chemical reagent, is also 

 placed inside the helix and the plant is attached to the 

 second Lever. The spots of light are so adjusted that one 

 lies immediately above the other. The two specimens are 

 thus subjected to the same temperature-variations, and the 

 variation of the second curve from the standard exhibits the 

 effect of the reagent. 



I can here barely indicate the very extended line of 

 inquiry thus opened out. With regard to the general effect 

 of drugs on death-response, it may be said that the displace- 

 ment of the rigor- point varies with the tonic condition of the 

 tissue, the nature of the drug, and the strength of the solution. 

 Out of several possible cases, I shall here give only a few 

 simple instances. 



Duplication of rigor-points. — One very curious effect 

 of certain chemical reagents, such as ether, lies in the ex- 

 hibition of two distinct points of rigor, instead, as normally, 

 of one. This effect is very easily seen, in the spasmodic 

 death- response of Mimosa. We take a specimen, and subject 

 it to continuous rise of temperature, in water, which contains 

 a small quantity of ether. It will be remembered that, under 

 normal conditions, the first down movement of the single 

 composite spasm of death-response took place in young 

 leaves at an average temperature of 59/5 ° C, the second 



