roNOLusroNs hkoakdinc i'roi.ifkka'I'ion. 39 



all cjiscs strictly iiH'chaiiical. 'riic runctioii of prolit'crat ion in most 

 cases is und()iil)t(Mlly to rcpnir an injurv. 



From the numerous ohscrvations dealt ^vith in detail in the jireced- 

 in<; paijes a number of conclusitjus seem to !)(> warranted. The })he- 

 nomena considered are very complicated, and consequently (mly a 

 few jjeneralizations are made. 



(1) In a larji^e number of varieties of American upland cotton 

 proliferation has l)eeTi found to occur in .")! ])cr cent of the cases of 

 weevil attack u|)on s<|uai('s and in .">.") jx-r cent of tlic cases of similar 

 attack upon i)olls. 



(2) Eliminating,' a certain ])ercenta^e of mortality, which was found 

 in cases where no proliferation occurred. th<> increased rate of mor- 

 tality in all weevil staii;es a])])arently caused by proliferation w^as, 

 ill squares 1.S.5 per cent and in bolls 6.3 per cent. 



(3) Ordinary variations in climatic cimditions seem to have com- 

 paratively little effect uj)on the proportion of injuries ])roliferating, 

 although hot, dry weather |)laudy increased the mortality occurring 

 without regard to the presence of ])roliferation. 



(4) Contrary to a j)revious tentative conclusion, based u})on a 

 much smaller number of observations." the uj)land American varieties 

 seem to be somewhat on a. j)arity so far as the tendency toward ])ro- 

 liferation is concerned. 



(o) The application of different fertilizers to cotton has thus far 

 failed to show any tendency toward increasing the |)roliferation. 



(()) Proliferous tissue is n(>t toxic to weevils. Death results in 

 most cases in a mechanical way from simple pressure. 



(7) Proliferation is caused by the attacks of a number of different 

 insects, and is easily produced artificially by ne<>(lle jnmctures. Its 

 stimulation appears to be from mechanical irritation, and, conse- 

 quently, a secretion on the ))art of the insect docs not .seem to be 

 essential. 



(5) Proliferation occurs conunonly in j)lants other than cotton as 

 the result of insect attack or from mechanical injury. It has been 

 noticed in the seed jxxls of several species of Leguminosu' and in differ- 

 ent sj^ecies of Capsicum. 



PRACTICAL APPLICATION OF CONCLUSIONS FROM THIS STUDY. 



The fuiidamentalpurpose under-lying all this study of pr'oiiferation. 

 its causes and :ts ctfeets, is to learn, if possible, facts which may be 

 made of jiractical use in the effort to grow a pr-oHtaltl(> crop of cotton 

 in the area infe>ted by the boll weevil, either- l»\- so corit r-olling the 

 multii)lication of the weevil as to reduce its injur-y to a sutVerable 

 <|uantity, or- by r-aising the croj) so as to avoid th<' serious injurv 

 which the pest has shown itself capable of producing under the >vstenr 



oBul. N<>- -"'l. Hiironii of Knfotnolog}', U. 8. iVpl. of Agric, p. 134. 



