COUNTINGS OF FLARED AND FALLEN SQUARES. 45 



The adaptive character of this habit of shedding the parasitized 

 squares seems to be confirmed by the fact that it depends upon the 

 existence of a special layer of soft cells which readily break down 

 when the bud is injured. Many plants have such cells as a means of 

 shedding their fruits, but they seem not to be prevalent among the 

 relatives of the cotton. The cotton itself does not drop the ripe bolls, 

 and even the empty shell often remains long after the seeds are gone. 



The drier the climate the more effective is the prompt shedding of 

 injured squares. Whether there are other adaptations thus especially 

 suited to dry climates is not yet known, our studies having been con- 

 fined mostly to humid regions. 



Dr. Edward Palmer, who has spent many years in botanical ex- 

 plorations of the dry plateau region of Mexico and who discovered 

 that the boll weevil was a cotton pest, states that in several localities 

 where the cotton was formerly grown without difficulty the introduc- 

 tion of irrigation improvements has proved disastrous. With the 

 assistance of the moist soil the weevils are now able to reach maturity 

 in large numbers and complete the devastation of the crop, quite as 

 in Texas. The irrigated soil affords a situation favorable for the 

 development of the larvae in the fallen squares. 



This is said to have been the case about Parras, and at Rio Verde, 

 below San Luis Potosi. The culture of cotton has declined also in 

 the u Huasteca Potosina,' 1 the tropical district between San Luis and 

 Tampico, and on the Pacific side of Mexico, along the Santiago River 

 above San Bias, as well as about Tepic. Doctor Palmer saw cotton 

 growing in a wild condition in the fences at the old mission, San Jose 

 de Guaymas, 6 miles from the commercial port; again at Mulege, 

 Lower California, across the Gulf from Guaymas, the latter a much- 

 branched, prolific tree, producing a nankeen-colored lint. About 

 Guaymas cotton was formerly utilized by the Indians as tinder, after 

 being dipped in a solution of saltpeter. The same facts were observed 

 by Dr. L. O. Howard in 1899 at San Jose de Guaymas. 



COUNTINGS OF FLARED AND FALLEN SQUARES. 



An attempt was made in connection with our Guatemalan experi- 

 ment to secure data on which a definite statement might be based 

 regarding the extent to which the different varieties were protected 

 by their involucral characters, but the problems are too complex to 

 be reached except by more elaborate statistical studies than were prac- 

 ticable at that time. 



Countings were made, for example, of the flared and fallen 

 squares — that is, of those which it might be supposed that the weevils 

 have injured — and of the number of weevil larva?, proliferations, etc., 

 found inside them. The results in percentages do not agree, however', 



