at different periods of the Day. 257 



mere coincidences, for there is little accordance between the plants 

 at other times ; for example, if we compare the Vine and Jerusalem 

 Artichoke as to their rate of growth at other periods near to those 

 when they are alike, we again find nothing but dissimilitude. 

 Thus, 



Here we see that although the Vine and Sweet Willow agreed 

 on two occasions very near about the same time, they otherwise 

 differed in the most singular manner. Jn the night of July 20th, 

 the Vine was just above its average, but the Jerusalem Artichoke 

 was not half way up to its average ; and so on in the other cases. 



If we next proceed to examine what the circumstances were 

 which favoured or retarded the growth of the experimental plants, 

 it will be found that there is scarcely more possibility of deter- 

 mining that point than of reconciling their differences with each 

 other. 



Plants are always said to grow fastest during a thunder storm, 

 the peculiar electrical state of the atmosphere at that time being 

 regarded peculiarly favourable to growth. Heat also is looked upon 

 as a powerful cause of rapid developement, especially if in combina- 

 tion with moisture ; on the other hand, cold is thought to produce 

 the contrary effect. Finally a brisk wind, as well as bright light, is 

 believed to impede vegetation, while warm overcast weather is 

 favourable to growth. But the actual results hardly confirm 

 those opinions. 



VOL. HI. 2nd series. 2 L 



