

VITALITY AND GERMINATION OF SEEDS. 243 



Permanganate METHOD OF ESTIMATING GROWTH IN 

 LENGTH AND CURVATURE OF KaDICLES. 



The experiments were performed chiefly with Peas, as 

 with these the best results were obtained, owing to the 

 rapid growth and relatively strong vitality of the primary 

 radicle. The radicles of Peas, of lengths varying from one 

 to six inches were immersed in a solution of potassium 

 permanganate, made by dissolving a few grains of the salt 

 in one pint of water. This forms a solution which is 

 neither so strong as to injuriously act upon the radicles nor 

 so weak as not to produce the desired result. In a period 

 of time varying from 2 to 6 hours, the time varying 

 according to the strength of the solution and the condition 

 of the radicles experimented with, a brown deposit is 

 formed over the entire surface of the immersed portion of 

 the radicle. This is due to the decomposition of the per- 

 manganate, oxide of manganese being deposited on the 

 root, free oxygen being given off and probably being at 

 once absorbed by the radicle, whilst caustic potash is set 

 free but at once turned into potassium carbonate by the 

 carbonic acid gas given off by the radicle. In some cases the 

 deposit is formed more thickly just over the meristematic 

 region of the growing apex. This is not, however, due to 

 the greater exhalation of carbonic acid gas at that point 

 causing a greater deposition of the oxide of manganese 

 but is due to the organic material and micro-organisms 

 which protected by the root cap, accumulate there, causing 

 as organic material a greater decomposition of perman- 

 ganate and hence a greater deposition of the oxide than 

 elsewhere. If a Pea or Hemp seedling of a few days 

 growth be entirely immersed in the solution, at the end 

 of an hour the entire root system is browned whilst on the 

 stem and leaves no deposit is formed, and even after 

 several hours, when the solution has penetrated and the 



