38 PROLIFERATION 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 been made in two species of peppers 
in connection with the work of the pepper weevil (Anthonomus eneo- 
tinctus Champ.). Proliferation was very distinct in 93.5 per cent of 
the pods 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 peppers proliferation was found in 
about 38 per cent of those examined and in about 34 per cent of the 
cases of simple feeding punctures. Among the 300 pepper pods" 
examined no trace of mR resulting fen the proliferation was 
seen. ? 
Among other plants no special observations seem to have been 
made to determine the presence or absence of proliferation, but it 
may be allowable to state here that a similar formation, which has_ 
every appearance of being homologous with susie an in cotton 
has been observed by Mr. F. C. Pratt in the pods of garden peas, by 
Mr. 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 special inves- | 
tigation shall be made of the occurrence of proliferation in other 
plants than cotton it will be found a not uncommon phenomenon i in 
very widely separated species of plants.* Naturally, it may not be. 
expected to occur in response to the great majority of insect injure 
since it depends upon a number of 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 uniformly essen- | 
tial. There must be a cell injury which is not sufficiently severe to 
overcome immediately the vital force of the injured organ or tissue. 
Proliferation is simply the manifestation of a natural intevene tend= 
ency of plant cells to respond to an encountered irritation by multi-, 
plying or forming new cells. It is evidently a method of self-defense, 
and in the case of cotton the irritation appears to be in nearly 
+ 
aThe possible general occurrence of proliferation as the result of insect attack is shown 4 
by the following quotation relating to Anthonomus quadrigibbus Say on apple, by Pro 
C. S. Crandall: Pd 
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 th a 
bottom, but often grew as wart-like excrescences from small areas on the sides of the cavities. In» 
several instances dead larve were found pressed close to the cavity wall by these intruding cell masses :4 
(Bul. 198, Ill. Exp. Sta., page 528.) 
