THE ASH OF PLANTS. 197 



healthy growth, produced new shoots only at the expense 

 of the older leaves. In similar trials oats gave a small 

 crop of ripe seeds when chlorine was not supplied. 

 When, however, the seeds thus obtained nearly free from 

 chlorine were vegetated in a solution destitute of this 

 element they failed to produce seed again, though their 

 growth and reproduction were normal when chlorine 

 was furnished them in the nutritive solution. 



In Plate I, X shows the extent to which, in Nobbe's 

 cultures, buckwheat developed when vegetating for 3 

 months in a solution destitute of chlorine, but otherwise 

 fully adapted to nourish plants. 



In view of all the evidence, then, it would appear 

 probable that chlorine is needful for the cereals, and 

 that when the seed and nutritive media (soil or solution 

 and air) are entirely destitute of this element fruit cannot 

 be perfected. It is probable that in the cases where 

 fruit was produced in supposed absence of chlorine this 

 substance in some way gained access to the plants. 



Until further more decisive results are reached, we 

 are warranted in adopting, with regard to chlorine as 

 related to agricultural plants, the following conclu- 

 sions, viz.: 



1. Chlorine is never totally absent. 



2^ If indispensable, but a minute amount is requisite 

 for a very considerable vegetative development. 



3. Some plants, as vetches and peas, require a not in- 

 considerable amount of chlorine for full development, 

 especially of seed. 



4. The foliage and succulent parts may include a 

 large quantity of chlorine that is not indispensable to 

 the life of the plant. 



Silica is not indispensable to Plants. — The numer- 

 ous analyses we now possess indicate that this substance 

 is always present in the ash of all parts of agricultural 

 plants, when they grow in natural soils. 



