at different periods of the Bay. 



Ill 



Doubtless the plants under experiment were to some small extent 

 affected by variations between these degrees, but 65 is always too 

 high to allow of any serious impediment to vegetation, nor do I 

 perceive any apparent connection between fast and slow growth, 

 and the temperature of the external air. For instance the slowest 

 growth of the Willow took place with the external temperature at 

 50°, when it lengthened only .03, while with the external air at 

 34° it grew on another occasion as much as .56 ; the slowest growth 

 of the Fig was .00 with the external air 54°, and its fastest was .22 

 with the external air 34 ; the minimum growth of the Passion- 

 flower was .03, the external air being on one occasion 48° and 

 another 35°, but when it was 41° the Passionflower grew .70 ; and 

 so of the Vine: when the external air was 44° it only grew .04, 

 but when it was 40° it grew as much as .85. This evidence proves 

 I think conclusively that in the cases under experiment the tem- 

 perature of the external air in no way affected the rate of growth. 



The next question that arises is whether the amount of light 

 can be supposed to have produced any influence. If we compare 

 the degree of light under which the more remarkable growths were 

 made, and which are marked + and — in the tables, we shall find 

 the following result 



Fast growth. Cloudy or Foggy. Clear. 



Cloudy or Foggy. Clear. 



If we are to judge from the comparison of some of these ex- 

 treme cases, we should infer that plants grew fastest in cloudy 

 weather, under the influence of diminished light, and slowest in 

 clear bright weather, when light is abundant, as seems to be the 

 opinion of Miinter above quoted. Thus in the Vine, out of 10 



