Chap. IV] TROPICAL DISTRICTS CONSTANTLY MOIST 



Wicsner 1 made a number of determinations of the amount of 

 light in the orchid quarter of the botanic garden at Buitenzorg. 

 The orchids are cultivated there on stems of species of Plumiera, in 

 the shade of lofty trees of Evia acida, Bl. 



The brightness in the orchid quarter was on the average i/io-8 of 

 the full daylight, and the diffuse front light on the stems of the 

 Plumiera trees was on the average 1/60-1/65 of the total daylight 

 (I maximum = 0-025-0-023). When the sun shone, the intensity 



Fig. 169. Tillandsia usneoides. Fragment of a shoot. Natural size. 



of the light from above rose to 1/4-7-1/7-7 of full daylight (I maxi- 

 mum = 0-319-0-194). 



The following orchids were growing well : Agrostophyllum javani- 

 cum, Bl., Eria ornata, Lindl., Spathoglottis plicata, Bl., Thelasis 

 carinata. Bl. Others, on the contrary, appeared to feel the want 

 of sufficiently intense light ; for instance, Thelasis elongata, BL, 

 Dendrobium acuminatissimum, Lindl., Coelogyne Rochusseni, De 



Vriese, C. Lowii, Pont., C. macrophylla, 



t" •• i. T5- i7 j i • 1 tt 1 r\ Fig. 168. Tillandsia 



Te.jsm. et Binn, Vanda tricolor, Hook., On- llsneoides . Sprig . 0ne - 



cidium ampliatum, Lindl. fifth natural size. 



1 See p. 55. 



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