'Rby^o'lds— Action of Metameric Compounds on Plants. 615 



■was very different fj-om that observed, in jS'o. 3 ; the stem did not 

 elongate much, but the leaves rapidly developed in length, breadth, 

 and substance, and assumed a healthy deep-green hue. It was no- 

 ticed, however, that the development was less satisfactory where the 

 solution of thiocarbamide was alone used for watering, than where 

 there was a washing of the soil with pure water between two doses ; 

 in the former case the edges of the lower leaves becoming discoloured 

 and thin. The reason for this is not far to seek ; for the thiocar- 

 bamide is known to undergo partial reconversion into sulphocyanate 

 in aqueous solution, and more especially in presence of such decom- 

 posable bodies as are found in the soil. The check in development of 

 the plant doubtless followed this partial reversion. 



With the slight modification in the treatment just referred to, the 

 plant developed remarkably; until, on the 1st of December, it was 

 in the state described below. 



No. 1 Plant {i. e. that treated with plain water) grew rapidly, and 

 soon outstripped the others in height, but its stem and leaves were 

 poor and thin as compared with I^o. 2. 



The following Table contains the measurements, &c., of the plants, 

 on the 1st of December : — 





" No. 1 

 (Water). 



No. 2 

 (THocarbamide) . 



No. 3 

 (Sulphocyanate). 



Total height in incliea from 

 surface of soil, .... 



Number of leaves, .... 



MairiTnum length of leaf in 

 inches, 



Maximum breadth of leaf in 

 inches, 



Number of seed pods in diffe- 

 rent stages of development, 



Nimiber of seed pods well de- 

 veloped, 



31 23 

 15 U 



91 ' 151 



41 6 



9 15 



1 



1 11 



12 

 13 



8 



2i 

 None. 

 None. 



Corresponding results were obtained with the other sets of tobacco 

 plants. 



The next step would obviously be the determination of the relative 

 proportions of nicotine derivable from the plants ; but the amount of 

 material at my disposal proved insufficient for the purpose. I hope, 

 however, to be able to grow a considerable quantity during the ensu- 

 ing summer, and to repeat the experiments. 



