626 Journal of Agricultural Research voi.xx,No. 8 



the methods of the Association of Official Agricultural Chemists (2) being 

 used. 



Water extracts of the sprouts, skins, and tubers were prepared by 

 macerating 50 gm. of the moist samples with a pestle in a mortar, then 

 rinsing the material into a graduated flask with water, adding 10 cc. of 

 toluene and making up to 500 cc. with water. The flasks were shaken 

 each minute for the first 5 minutes and then every 15 minutes for the 

 first hour, after which they stood overnight at room temperature. The 

 next morning the liquid was removed with a pipette and filtered through 

 glass wool and then through filter paper. The following determinations 

 were made on the water extracts: (1) Soluble nitrogen, employing 

 25 cc; (2) soluble phosphoric acid, employing 50 cc; (3) ammonia 

 nitrogen, employing 5 cc, by the aeration method of Folin (14) and 

 nesslerizing the volatile nitrogen; (4) separation of nitrogenous com- 

 pounds, employing 100 cc. 



In making a separation of the nitrogenous compounds, 100 cc. of the 

 solution were acidified and heated to boiling. The coagulable protein 

 was removed first, then the remaining protein, by precipitation with 

 dilute lead acetate solution. The lead was removed from the filtrate 

 with hydrogen sulphid, the lead sulphid being filtered off and washed 

 with a dilute solution of hydrochloric acid through which hydrogen sul- 

 phid had been passed. The solution containing the amino acids, amids, 

 etc., was then made to volume, and the total nitrogen was determined 

 in an aliquot. The largest portion of the fdtrate was precipitated with 

 phosphotungstic acid according to the Hausman method, and the nitro- 

 gen in the filtrate (monoamino and amid nitrogen) was determined. 

 The nitrogen of the diamino acids and other bases was obtained by 

 difference. 



Copper was determined in certain of the samples by the colorimetric 

 method, using potassium ferrocyanid and standard solutions of copper 

 sulphate. This method, which has been shown to yield identical results 

 with the electrolytic method, has the advantage of giving accurate 

 results when minute amounts of copper are present and of being appli- 

 cable when the electrolytic method is not. 



RESULTS OF ANALYSIS 

 RELATIVE WEIGHTS OF SPROUTS AND TUBERS 



The samples of sprouts, skins, and tubers numbered 1 to 3 and 4 to 6 

 (Table I) were of the Green Mountain variety. On February 1, 19 19, 

 the sprouts on these two sets of tubers constituted 4.6 per cent of the 

 total moist weight of sprouts, skins, and tubers. Samples 1,2, and 3 were 

 from vines sprayed with 5-5-50 Bordeaux spray, while samples 4, 5, 

 and 6 were from unsprayed vines. Samples 7,8, and 9 (sprouts, skins, 

 and tubers) were from Irish Cobbler plants. At the time of analysis, 



