2o8 Journal of Agricultural Research voi. iii. No. 3 



0.035 to 0.037 P^r cent of Fe^Og. Since the samples were small, it is felt 

 that the figures merely show that practically the same percentages of iron 

 were present in all the plants. Thus, the quantities of iron in the different 

 lots of plants would vary as their dry weights. 



In all the experiments the plants which received no iron in either flasks A 

 or flasks B were strongly chlorotic, the chlorosis commencing about 6 to 10 

 days after the plants were put in the solutions. The plants receiving dia- 

 lyzed iron or ferric chlorid in flasks B were also strongly chlorotic, 

 although they were somewhat greener than the check plants without any 

 iron, and the chlorosis was later in appearing. The plants which had the 

 ferric chlorid added to the other nutrient salts in flasks A were of a normal 

 green color. 



The root development varied greatly in the different flasks. In all 

 the flasks A which contained the complete nutrient solution without iron 

 the root development was good, the main roots being long, with numerous 

 long laterals. The roots in flasks B which contained only distilled water 

 made very little growth and had few laterals. The roots in flasks B 

 which contained only ferric chlorid made even less growth than those in 

 distilled water. As soon as the roots penetrated the ferric-chlorid solu- 

 tion, the root tip appeared killed and no roots penetrated the solution 

 for any distance. The roots in flasks B which contained dialyzed iron 

 developed much better than in distilled water. During the latter stages 

 of growth particularly a few heavy roots developed in the dialyzed iron, 

 but these roots carried very few laterals. The oven-dry weights of the 

 roots in flasks B given in Table III do not really give a comparison of the 

 root developments in the solutions, for the reason that the weights of the 

 roots in flasks B, Nos. 31-60, were made up chiefly of root "stubs" — 

 heavy roots which started out from the plants but did not develop in the 

 distilled water or ferric-chlorid solution. The larger the top growth, de- 

 pendent on the amount of iron obtained, the more root "stubs" devel- 

 oped. For instance, flasks B, Nos. 41-46 and Nos. 36-50, had 0.174 gni- 

 of roots, while Nos. 31-35 and Nos. 36-40 had but 0.077 gm. of roots. 

 As a matter of fact, the root development in the solution was less in the 

 first case than in the second. 



DISCUSSION OF RESULTS 



The poor development of the roots in the flasks B was, of course, due to 

 the well-established toxicity of unbalanced solutions — in this case of 

 single salts or distilled water.' Because of the injury resulting from the 

 iron solutions it is impossible to draw a very sharp conclusion concerning 

 the assimilation of colloidal iron. Although the roots developed better in 



' True holds the injury from ordinary distilled water "but a spedal case of the general type of injury 

 wrought on cells by unbalanced solutions."— True, R. H. The harmful action of distilled water. In 

 Science, n. s., v. 39. no. 999. P- 29s- 1914. 



