CONCLUSIONS REGARDING PROLIFERATION. 39 | 
all cases strictly mechanical. The function of proliferation in most 
cases is undoubtedly to repair an injury. 
From the numerous observations dealt with in detail in the preced- 
ing pages a number of conclusions seem to be warranted. The phe- 
nomena considered are very complicated, and consequently only a 
few generalizations are made. 
(1) In a large number of varieties of American upland cotton 
proliferation has been found to occur in 51 per cent of the cases of 
weevil attack upon squares and in 55 per cent of the cases of similar 
attack upon bolls. 
(2) Eliminating a certain percentage of mortality, which was found 
in cases where no proliferation occurred, the increased rate of mor- 
tality in all weevil stages apparently caused by proliferation was, 
in squares 13.5 per cent and in bolls 6.3 per cent. 
(3) Ordinary variations in climatic conditions seem to have com- 
paratively little effect upon the proportion of injuries proliferating, 
although hot, dry weather plainly increased the mortality occurring 
without regard to the presence of proliferation. 
(4) Contrary to a previous tentative conclusion, based upon a 
much smaller number of observations,“ the upland American varieties 
seem to be somewhat on a parity so far as the tendency toward pro- 
liferation is concerned. 
(5) The application of different fertilizers to cotton has thus far 
failed to show any tendency toward increasing the proliferation. 
: (6) Proliferous tissue is not 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 needle punctures. Its 
| 
stimulation appears to be from mechanical irritation, and, conse- 
quently, a secretion on the part of the insect does not seem to be 
essential. 
: (8) Proliferation occurs commonly in plants other than cotton as 
the result of insect attack or from mechanical injury. It has been 
noticed in the seed pods of several species of Leguminose and in differ- 
ent species of Capsicum. 
PRACTICAL APPLICATION OF CONCLUSIONS FROM THIS STUDY. 
i 
The fundamental purpose underlying all this study of proliferation, 
its causes and its effects, is to learn, if possible, facts which may be 
made of practical use in the effort to grow a profitable crop of cotton 
in the area infested by the boll weevil, either by so controlling the 
‘multiplication of the weevil as to reduce its injury to a sufferable 
quantity, or by raising the crop so as to avoid the serious injury 
which the pest has shown itself capable of producing under the system 
rt es - — 
@ Bul. No. 51, Bureau of Entomology, U.S. Dept, of Agric., p. 134. 
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