152 EXPERIMENT STATION. [Jan. 



leaf was especially noticeable in such sprouts as asli, poplar and 

 plane tree, and sometimes occurred also on chestnut and oak, 

 although it may be mentioned that they were occasionally very 

 much distorted. 



When the leaves were simply abnormally large it was foimd 

 that tlie structure of the cells and their relative positions were 

 analogous to a healthy, normal leaf, but that they were rela- 

 tively much larger, and were of a stiffer texture than the nor- 

 mal specimens. 



Very often it was found that the cell contents, especially the 

 coloring matter, were brought into undue prominence, richly 

 colored red leaves being of frequent occurrence. Occasionally, 

 also, leaves having a decided yellow color, but otherwise ap- 

 pearing strong and healthy, were observed. This excessive col- 

 oration was evidently due to the abnormal deposition of pigment 

 or activity of colored cell sap. When the leaves were green, the 

 color seemed to be deeper than that of normal specimens. 



The second form of the malformation has much the appear- 

 ance of that caused by overfeeding, or excessive use of nitrates ; 

 i.e., a severe distortion of leaves, but in this case accompanied by 

 excessive ju-oduction, usually smaller in size than the normal, 

 but thickly clustered. Distorted leaves did not usually show 

 much abnormal coloration, but occasionally a reddish or yellow- 

 ish color was observable. 



Usually the leaves were much more numerous and very badly 

 distorted, the veins and ribs being especially twisted in various 

 ways. The texture of the leaf was very stiff, much more so 

 than in the case of the abnormally large leaves, the tissue having 

 hardly any elasticity, and breaking easily, with a crackling 

 sound. Plates I. and II. (Figs. 1, 2 and 3) show the two forms 

 of this trouble better than mere description. 



There is a remarkable dearth of literature bearing on this 

 specific trouble, although much has been written in a general 

 way on somewhat similar physiological troubles, but dealing 

 principally with field crops and forced plants. In the reports of 

 the various experiment stations will be found more or less lit- 

 erature on physiological troubles, and Woods,* Suzuke,^ Stur- 



1 U. S. Dept. Agr., Bur. Plant Ind., Bui. No. 18. 



2 Bui. Col. Agr., Tokyo, Vol. IV., repts. for 1900. 



