67 



The four-week plant and Gllmatlo data . 

 Exposed Stations . 



The general plan of treatment adopted in the case of the 

 two-w^ data will be follwed in the present Usoussion of the 

 four-we°k periods. It will Le possible, however, to treat the 

 four-week climatic indices briefly since the graphs of these 

 factors for the longer growing periods cover approximately 

 the s ime season at each station as the two-we-k climatic graphs. 

 In accordance, th^n, with the plan previously laid down for dis- 

 cussing the two-week data, three divisions of the four-wet^k 

 data will be made; (1) A brief consideration of the climatic 

 graphs; (2) A consideration of tho relations between the plant 

 graphs. f3) Attempts to correlate the ^lant and climatic 

 graphs. 



The four-week climatic data . 



It will be rememHiered that the cul turns were started 

 every two weeks and that each grew for a nericd of four weeks. 

 The four-week periods thus over-lap, and, as has been mentioned, 

 avera?-es of the climatic factors for these overlapping periods 

 fcrm a smoother graph than averages for the two-werk periods. 

 The result of averaging over the longer overlapping periods 

 is to eliminate from the graph all the smaller fluctuations. 

 The fTir-week graphs therefore show the general seasonal march 

 of the index values for various stations better than do the 

 two-week while the latter show the details of the seasonal 



