HORTICULTURE AND LANDSCAPE GARDENING. 



131 



•of those exposed four inches. The effect of the ozone in checking the 

 growth of the roots was very remarkable, especially with the wheat plants. 

 In those not exposed to ozone, the roots attained a length equal to about one- 

 fourth the height of the stem. In those exposed to it, the roots, after start- 

 ing, almost immediately ceased to grow. The strongest plant attained a 

 height of six inches and developed six rootlets, averaging only three-sixteenths 

 of an inch in length, while those not exposed to ozone had many roots 

 ■exceeding two and a half inches. As a whole, the roots produced by the 

 plants under the influence of ozone did not exceed one-tenth of those pro- 

 duced in its absence from an equal number of healthy seeds." 



Seeds placed in an atmosphere from which all carbonic acid had been 

 removed germinated as readily as those in atmospheric air. Others placed 

 in an atmosphere of carbonic acid did not germinate, although they after- 

 wards germinated readily when exposed to the atmosphere. 



Subsequent experiments were made by the same investigator with various 

 organic and inorganic substances.* In one instance twelve glasses of twelve 

 and one-half oz. water each were prepared with solutions as follows: 



8. A pair of zinc and copper plates con- 

 nected above the surface by a wire 

 and plunged in plain water. 



9. Same, acidulated by three drops hydro- 

 chloric acid. 



10. Plain water for comparison. 



11. Five grs. sulphite of soda. 



12. Five grs. chlorate of potassa. 



A thin muslin was placed over the liquids so as to dip into them, and on 

 this were placed in each case, twenty grains of wheat. The most rapid ger- 

 minations during a period of six days occurred in solutions Nos. 4, 10, 11. 

 At the end of the sixth day the poorest results were obtained fromlSTos. 1, 2, 

 3, 9. The following table shows the per cent of germination, and the pro- 

 portional amount of vegetation at the end of seven days: 



1. One drop sulphuric acid. 



2. Two drops nitric acid. 



3. Three drops hydrochloric acid. 



4. Five grs. bicarbonate of potash. 



5. Five grs. dry carbonate of soda. 



6. Ten drops of rather weak liquid ammo- 



nia. 



7. Five grs. bromide of ammonia. 



* Amer. Jour. Sci. Incl. Ser. xliii., 197. 



