Sunrise and Growth. 



257 



when the early rays were cut off and resumed their green colour 

 when the rays were readmitted, that light acting upon the chlorophyll- 

 granules, and not temperature, was the true explanation. 



On March 27th the further experiment was made of screening peas 

 from the time they were sown. It was also desired to eliminate 

 the possibility of sunset or of reflected rays having vitiated the 

 former results. Some of the seedlings in Rows I. and II. had been 

 observed to have received more sunset rays than others, and also 

 some reflected rays from a house window 20 yards away. Three 

 more plots, each 5ft. long, were planted with selected seeds of Dwarf 

 Stratagem peas, 4 to 6 inches apart, where they would receive the 

 earliest rays, but no direct sunlight after i5h. 30m. Plots A and B 

 were provided with iron screens, the former io| inches wide by 8 

 inches high, and the latter 14 inches wide by 9 inches high. The 

 peas in Plot A, which were furthest from the screen, were arranged 

 to receive the rays about half-an-hour before those nearest to the 

 shadow thrown by the screen, while those actually in the shadow 

 would not receive any direct rays till after 8h. 42m. The screen at 

 the head of Plot B was perforated with 7 holes the size of a three- 

 penny piece, that the effect of intermittent light, if any, might be 

 watched. Plot C was used as a control without any screen at all. 



At sunrise on March 28th the ground in Plot A up to within 18 

 inches of the screen was lit gradually from 6h. 50m. up to 7h. 3m. 

 On April 2nd the first seed appeared above ground. It was the end 

 seed (No. i) furthest from the screen. Rain fell during the day, and 

 on the 3rd the majority of the peas showed their leaves above the 

 surface in all the plots. The first table gives the times of 

 incidence of direct rays upon each plant in Plot A from April 8th 

 onwards. No. 8 was just on the edge of the deep shadow ; Nos. 3, 4, 

 7 had not come up. The next table gives the measurements which 

 were taken on April, 14th. 



Plot A.— Times of Incidence of Rays, April 8 — 12. 



No. 



I 

 2 



5 

 6 



8 



Plot A. — Dimensions of Plants, April 14th. 



Stem. 



Diam. 

 mm. 



2 

 2 

 2 



I 



Height. 



mm. 

 40 



35 

 40 



15 



25 



Number of 



Leaves. Branches, Tendrils. 



7 

 6 



6 



5 

 5 



17 



