1917] Ayres : Nutrient Solution on Plants Grown in Sand Cultures 363 



line which will clearly segregate the injury to the various plants 

 of a large series of this kind into well-defined groups since there 

 is always more or less overlapping. An attempt was made, how- 

 ever, to divide the plants into groups which would show in each 

 case a characteristic type of injury. 



(a) This group was made up of plants which were very much 

 stunted, being less than 8 cm. in height and in every case showed 

 a marked chlorosis which was clearly attributed to a low supply 

 of nitrogen. The plants in this group were I A 1, I A 2, I A 3, 



I B 1, I B 2, I B 3, I C 1, I C 2, I C 3, I D 1. 



(&) This group was somewhat taller, from 13 to 21 cm. high, 

 but clearly stunted in growth. These plants showed less chlo- 

 rosis, since nitrogen was present in sufficient quantity to provide 

 close to the optimum supply in all cultures with the exception 

 of II D I and I D 2, where there was a distinct chlorosis due to 

 the low nitrogen supply. Plants showing this type of injury were 



II A 1, II B 1, II C 1, II D 1, I D 2. 



( c ) Plants in this group showed a more serious type of injury 

 than any of the other plants. They were more than 40 cm. in 

 height, but were very spindly (pi. 15). The whole plant showed 

 marked chlorosis, which affected the lower leaves most severely 

 and soon resulted in their death. This type of plant was found 

 in cultures I D 3, II B 2, II B 3, II C 2, II D 2. II D 3, II D 4, 



III D 1, III D 2, III D 3, III D 4, and III D 5. 



(d) The plants of this group were decidedly more vigorous 

 than those of the preceding groups, as indicated by their in- 

 creased height and better color. Indeed, they seemed to be per- 

 fectly normal. The following cultures were classed in this group : 



I C 4, I D 4, II C 3, II C 4, II D 5, III A 1, III A 2, III A 3, 

 III B ], III B 2, III B 3, III C 1, III C 2, III C 3, III C 4, III C 5. 

 The following plants were even better in appearance than those 

 just named : I A 4, I A 5, I B 4, I B 5, I C 5, I D 5, II A 2, II A 3, 



II A 4, II A 5, II B 4, II B 5, II C 5, III A 4, III A 5, III B 4, 



III B 5. 



A study of the above grouping indicates that chlorosis was 

 present wherever the nitrogen content was low, as was to be ex- 

 pected. The spindly growth characteristic of groups II D and 

 III D may also be due to the low supply of nitrogen. It seems 



