ENVIRONMENT OF THE BOLL 87 



There are many ways in which the environment of 



plants can be altered, but the simplest way of all is to 



make no attempt to control the surround- 



Methodof ingg ^ but s i m piy to rec ord the changes 



fetiidy* 



which naturally take place. This method 



is almost ideal for the study of developing cotton bolls 

 in an irrigated and rainless country. Each set of bolls 

 opening on each day will have passed through a slightly 

 different series of experiences from those opening on the 

 day before or on the day following. By arranging to 

 obtain continuous observations day by day throughout 

 the season, we can watch the effect of any particular 

 environmental effect upon bolls of every age. Since the 

 understanding of the following results depends on the 

 realization of this point, it may be dealt with a little more 

 fully (see also Appendix I.). 



We saw in the previous chapter some strong reasons 

 for concluding that any marked alteration of the 



environment on a certain day would affect 

 Age of Boll. _ , . , ,, ,. 



developing bolls of vanous ages according 



to the particular structural developments which were 

 progressing inside them at the time. Consequently, if 

 we apply the most severe modification possible, by killing 

 the plant outright, we shall not affect the length of the 

 lint in the old bolls, but we shall prevent it from becoming 

 any longer in the young ones. Similarly, since the thick- 

 ness of the lint hair wall is not laid down until the boll is 

 halfway through its maturation, we shall check any 

 further increase in thickness. 



Less severe modifications of the environment, such as 



