Disease in Plants. 187 



Moisture 8-86 



Oil 29-34 



*Albuminous compoiuids (flesh-forminc!; matters) . . . . 22-75 



Gum, mucilage, and sugar 7*58 



Woody fibre (cellulose) 24-69 



Mineral matters .. .. 6-78 



100-00 

 *Containing nitrogen 3*64 



Augustus VoEiiCKER. 



1 1, Salisbury Square, Fleet Street, U.C., 

 Dec, 1865. 



XVI. — upon the Nature of Diseases in Plants. 

 By Baeon Liebig.* 



Experiments on the Growth of Potatoes. 



Some plants, as for instance the potato, require an unusually 

 large quantity of alkalies or alkaline earths for their full develop- 

 ment. The object proposed in the experiments here described 

 was to discover the relative effects of soils containing these 

 elements in different proportions upon the growth of such a plant. 



The experiments were carried on in the Botanic Garden at 

 Munich, under the superintendence of Professor Nageli and 

 Dr. Zoller. Three boxes, numbered I., II., III., were filled with 

 coarsely-powdered turf, and sunk in the open ground. Each box 

 was about 5 feet long, 4 feet broad, and 1|- foot deep, thus con- 

 taining about 30 cubic feet of turf, of which the weight was 

 about 5 cwts. 77 lbs. Two of these boxes, II. and III. were 

 manured ; the third, I., contained natural turf. To the turf in 

 II. was added 863 grammes (= 1 lb. 12 oz.) of phosphate of 

 ammonia, 383 grammes (12|^ oz.) of sulphate of ammonia, and 

 378 grammes (12|^ oz. nearly) of carbonate of ammonia. To 

 the turf in III. was added 600 grammes (1 lb. 3 oz.) of phosphate 

 of soda, 250 grammes (J lb.) of phosphate of potash, 790 

 grammes (1 lb. 10 oz.) of carbonate of potash, and 500 grammes 

 (about 1 lb.) of gypsum. 



These manures were most carefully and intimately mixed with 

 the turf, and their proportions were so chosen that the turf was 

 about half saturated. Hence it was certain that no appreciable 

 quantity of them Avould be dissolved by watering and carried to 

 such a depth as to be beyond the reach of the roots of the plants. 



On the 9th of May 9 potato tubers were set in each box about 



* Translated from a paper communicated to the Journal of the Bavarian Agri- 

 cultural Society, 1864, p. 52. 



