284 -f. ^v. niavs. 



The object of tlie investigation was to discover wliat frac- 

 tion of the total sunlight readied plants growing in vai-ious 

 places. A few observations wei'e first taken in the open, and 

 the average ascertained. Then, with the smallest possible 

 delay, an observation was taken in the shade. In the latter 

 case usually only one observation was taken as there is less 

 possibility of error, owing to the paper taking longer to darken. 



The following are the most important of the general results 

 obtained. 



In the scattered type of bush, coast and midland, and in 

 the Yellow Wood bush, which will be described fully in the 

 second part of this paper, there is rarely more than -gi^ of the 

 full sunlight which penetrates to the ground at mid-day. In 

 some places we have the full succession of upper canopy, 

 lower canopy, under-shrubs, under-herbs, and great numbers 

 of lianes clind^ing up over the whole. In other cases the 

 upper canopv alone is so dense that practically nothing grows 

 underneath. This is the case with Xymalos monospora 

 for instance. There are all intermediate stages. If the 

 upper canopy is less dense the lower canopy may be more 

 dense, and if both allow a fair amount of light through them 

 there is more rank undergrowth. In the Yellow Wood bush 

 the upper and lower canopies of trees, together with the 

 lianes, absorb most of the light, and there is comparatively 

 little undergrowth. 



In the rocky stream Inish the amount of light which pene- 

 trates is much more variable. In the bed of the stream an 

 average of eight observations in different places gave -g^"- as 

 the amount. In other parts as little as -j^i^ was jigain recorded. 

 In places there are open gaps, but unless where these are very 

 wide, though apparently the actinometer is exposed to full sun- 

 light, the reading sliows that the full amount is not penetrating. 

 I'liis maybe due to the mantle of water-vapour that is always 

 present in the bush. 



In describing later this kind of bush it will be pointed out 

 that certain species of plants favour the denser shade, while 

 others prefer to have more light. 



