38 TKOLIKKKATION IN CONTROL OF BOLL WEEVIL. 



PROLIFERATION IN PLANTS OTHER THAN COTTON. 



The most definite and abundant observations of proliferation in 

 plants other than cotton have ])een made in two species of peppers 

 in connection with the work of tlie ])ej)])er weevil (AntJionomu.s seneo- 

 tlnctus Champ.). Proliferation was very distinct in 93. .5 per cent of 

 the j)()ds of sweet pepper which had been attacked by the pepper weevil. 

 It was also found to have formed in three-fourths of the feeding 

 punctures. In pods of the chili ])e])j)ef*s ])r()lif(n-ation was found in 

 about .3S per cent of those exanuned and in al)()ut 34 per cent of the 

 cases of simple feeding punctures. Among the 3()() pe])]ier pods 

 examined no trace of mortality resulting from the proliferation was 

 seen. 



Among other plants no special observations seem to have been 

 made to determine the ])resence or a])sence of proliferation, but it 

 may be allowable to state here that a similar formation, which has 

 every appearance of being homologous with proliferation in cotton, 

 has been observed by Mr. F. C. Pratt in the j)ods of garden peas, by 

 Air. C. R. Jones in the pods of cowpeas, by Mr. A. C. Morgan in the 

 buds of Callirrhoe involucrata, and by Mr. J. C. Crawford in the seed 

 pods of mesquite. It would appear probable that when s])ecial inves- 

 tigation shall be made of the occurrence of })roliferation in other 

 plants than cotton it will be found a not uncommon phenomenon in 

 very widely se])arated species of plants. " Xatia-ally, it may not be 

 expected to occur in response to the great majority of insect injuries, 

 since it depends upon a number ©f coincident favorable conditions, 

 and the presence or absence of some other and entirely unrelated 

 factor may prevent or obscure its formation even where some of the 

 essential favorable conditions are present. 



CONCLUSIONS AS TO NATURE AND SIGNIFICANCE OF 

 PROLIFERATION. 



In all cases, whatever the stimulant, one factor is imiformly essen- 

 tial. There must be a cell injury which is not sufliciently severe to 

 overcome immediately the vital force of the injured organ or tissue. 

 Proliferation is simply the manifestation of a natural inherent tend- 

 ency of plant cells to respond to an encoiuitered irritation })y nudti- 

 pl3ang or forming new cells. It is evidentl}" a method of self-defense, 

 and in the case of cotton the irritation appears to be in nearly 



a The possible general occurrence of proliferation as the result of insect attack is shown 

 by the following quotation relating to Anihonomiis quadr'Kj'ihhiis Say on apple, by Prof. 

 C. S. Crandall: 



Many of the egg-cavities cut into were found to be more or less completely filled by intruding cell 

 masses. These cell masses were quite firm in texture. Sometimes they invaded the cavity from tliQ 

 bottom, but often grew as wart-like excrescences from small areas on the sides of the cavities. In 

 several instances dead larva; were found pressed close to the cavity wall by these intruding cell masses. 

 (Bui. 198, 111. Exp. Sta., page 528.) 



