30 



CIRCULAR NO, 120, BUREAU OP PLANT INDUSTRY. 



being iDunctured or torn. Leaf-cut injuries, on the other hand, rep- 

 resent an actual destruction of some of the tissues of the leaf, leav- 

 ing irregular holes or marginal incisions. In single words, leaf-curl 

 may be described as distortion of the leaves, leaf -cut as mutilation. 

 In allusion to this distinction the word " tomosis " is proposed as a 

 technical name for the leaf-cut disorder, while the distortion caused 



Fig. 1. — Young plant of Egyptian cotton yiown at Lanham. Md. Tho lowcf li>aves arc 

 affected l).v leaf-cut and upper loaves by Ipaf-curl. (Natural si/c. i 



by the plant lice may be called '' hybosis." The insects inhabiting 

 the badly distorted upper leaves of figure 1 were identified by Mr. 

 Th. Pergande, of the Bureau of Entomology, as Aphis gossyjnl 

 Glover. 



And in addition to the open wounds that result from leaf-cut there 

 are usually some that have healed, giving a characteristic torn-and- 

 mended appearance. Such scars, lil\e other leaf-cut wounds, often 



[Cir. 120] 



