THE STIMULATION OP PLANT GROWTH BY MEANS OP WEAK POISONS 



29 



substances on the growth of potatoes. Although 

 the results are far from complete, they indicate 

 that magnesium carbonate, applied at the rate of 

 200 pounds per acre, and iron and manganous sul- 

 fate applied at the rate of 17 and 175 pounds per 

 acre respectively, exert a stimulating action on 

 the growth of potato tubers. The benefits of stimu- 

 lation were shown not only in the increased yield 

 of the tubers, but also in their improved quality. 

 The action of the same poisonous compound is not 

 always the same on different crops, just as the 

 feeding of different crops must vary. The action 

 will probably vary also on soils accord- 

 ing to their content of acids or alkalies. 



The application of small quantities of 

 organic substances having a toxic effect 

 at high concentrations is often beneficial, 

 especially when applied to certain un- 

 productive soils. Bulletin No. 28 of the 

 Bureau of Soils of the United States De- 

 partment of Agriculture describes the 

 beneficial effects of tannic acid and of 

 pyrogallol when applied in small quanti- 

 ties to an unproductive soil. The applica- 

 tion of tannic acid at the rate of one part 

 per million of soil increased the growth 

 of wheat seedlings about 75 per cent. In 

 another experiment, pyrogallol was added 

 at the rate of 500 parts per million of 

 soil. On soil so treated, the growth of 

 wheat plants was twice that on the un- 

 treated soil. While it is not probable that 

 the applicatipn of either of these last- pjg 47 

 named substances will be profitable for 

 the commercial grower, it is shown that growth 

 may be accelerated by a wide range of substances. 



Etherization. 



It may be in place to mention the action of anaes- 

 thetics on plant growth, since the anaesthetics 

 behave as poisons if they are allowed to act for any 

 length of time. The plants are inclosed in a tight 

 compartment and exposed for a short time to the 

 vapors of ether or chloroform. At the Government 

 Botanical Garden in Dresden, lilacs treated with 

 ether on October 19 produced blossoms November 8. 

 Another season the etherized plants blossomed 

 November 13. Etherization does not hasten the 

 blooming period of lilacs if the period of rest is 

 entirely completed before the anaesthetic is applied. 



The practice of etherization is meeting with 

 favor among the florists of France. In America 

 it has been applied with success to the forcing of 

 rhubarb and asparagus. Sandsten showed that chlo- 

 roform and ether had an accelerating influence on 

 seedlings, but they were injurious to narcissus. 



Experiments made at the Cornell (N. Y.) Experi- 

 ment Station gave interesting results. A Persian 

 lilac, Syringa vulgaris, was placed in the forcing- 

 house on November 24, after having been etherized 

 for 24 hours. Within five days many leaf-buds 

 were entirely open, and by December 11 the plant 

 was in full leaf. The flrst flower-buds opened on 

 December 6, and the plant was in full bloom on 

 December 25, just 31 days after the beginning of 



the experiment. A check plant did not reach full 

 bloom till six days later. When the plants were 

 exposed to ether fumes for a longer period, more 

 marked results were secured. A lilac etherized for 

 48 hours made a gain in coming to full flower of 8 

 days over the check plant; one etherized for 72 

 hours gained 10 days. Astilbe Japonica etherized 

 for 24 hours, in one instance was in full bloom a 

 month to five weeks before the check plant. Experi- 

 ments with bulbs also showed favorable results 

 from etherization (Pig. 47). Narcissus showed a 

 gain varying from two days to three weeks in 



Narcissus etherized (at the right) and not etherized (at the left) . 



coming to full bloom, results contradictory to those 

 secured by Sandsten. Two lots of Lilium longi- 

 Jlorum showed a decidedly taller growth, but no 

 gain in the time at which first blossoms appeared. 

 A third lot, which had been etherized for a longer 

 time, showed a gain in both time and height. [A 

 brief account of these Cornell Experiments, by J. 

 Eaton Howitt, and Claude I. Lewis, appears in 

 The Cornell Countryman, May, 1906 ; a bulletin of 

 the work has not appeared as this article is written.] 



Literature. 



The following references include most of the liter- 

 ature that has been published on plant stimulation : 

 Raulin, Etudes chimique sur la vegetation,. Ann. d. 

 Sci. Nat. Bot. [v] XI. 91, 1869; Richards, Die 

 Beeinflussung des Wachstums einiger Pilze durch 

 chemischer Reize, Jahrb. wiss. Bot. 30, 665, 1897 ; 

 Sandsten, The Influence of Gases and Vapors on the 

 Growth of Plants, Minn. Botanical Studies, Vol. 2, p. 

 53, 1898; Richards, The Effect of Chemical Irrita- 

 tion on the Economic Coefficient of Sugar, Bulletin, 

 Torrey Bot. Club, Vol. 26, 463, 1899; Ono, Ueber die 

 Wachstumsbeschleunigung einiger Algen und Pilze 

 durch chemischer Reize. Jour. College, Science, 

 Imperial University, Tokyo, Vol. 13, 141-186, 1900; 

 Loew, On the Treatment of Crops by Stimulating 

 Compounds, Bui. College Agriculture Impeijal Uni- 

 versity, Tokyo Vol. VI. 161-175, 1904 ; Latham, 

 Stimulation of Sterigmatocystis by Chloroform, 

 Bui. Torrey Bot. Club, Vol. 32, 337, 1905. 



