196 HOW CROPS GROW. 



considerable development in the absence of chlorine (the 

 minute amount in the seed itself excepted), presence of 

 chlorine is essential to the perfection of the fruit. 



Leydhecker came to the same conclusions as Nobbe 

 and Siegert regarding the indispensableness of chlorine 

 to the perfection of buckwheat. ( Vs. St., VIII, p. 177.) 



On the other hand, Knop excludes chlorine from the 

 list of necessary ingredients of maize, buckwheat, cress, 

 and Psamma arenaria, having obtained a maize plant 3 

 feet high, bearing 4 ripe seeds, harvested 23 " chlorine- 

 free seeds" from 5 buckwheat-plants, and raised 40 to 50 

 ripe seeds from more than one cress-plant, all grown 

 without chlorine. (Vs. St., XIII, p. 219.) 



Wagner also obtained, in absence of chlorine, maize- 

 plants 40 inches high, of 20 grams dry-weight. One of 

 these ripened 5 small seeds, of which two were proved 

 capable of germination ; but none of these plants produced 

 any pollen and they were fertilized with pollen from 

 garden-plants. (Vs. St., XIII, pp. 218-222.) 



From a series of experiments in water-culture, Birner 

 and Lucanus (Vs. St., VIII, p. 160) conclude that chlo- 

 rine is not indispensable to the oat-plant, and has no spe- 

 cific effect on the production of its fruit. Chloride of 

 potassium increased the weight of the crop, chloride of 

 sodium gave a larger development of foliage and stem, 

 chloride of magnesium was positively deleterious, under 

 the conditions of their trials. 



Lucanus ( Vs. St., VII, pp. 363-71) raised clover by 

 water-culture without chlorine, the crop (dry) weigh- 

 ing in the most successful experiments 240 times as much 

 as the seed. Addition of chlorine gave no better result. 



Nobbe (Vs. St., VIII, p. 187) has produced normally 

 developed vetch and pea plants, but only in solutions 

 containing chlorine. Beyer (Vs. St., XI, p. 262) found 

 exclusion of chlorine in water-culture to prevent forma- 

 tion of seed in case of peas ; the plants, after a month's 



