MINUTE STRUCTURE. 



71 



The presence of chlorophyll in the aerial roots of orchids is note- 

 worthy, and shows that the roots in these cases perform to some 



Fig. 10. Fragment of transverse section of stem of Cattleya intermedia, enlarged 200 diameters. 

 1, epidermis of one layer of thick-walled cells overlain hy thickened cuticle ; 2, liypodcrmis of large thick- 

 walled cells ; 3, fundamental tissue of soft thin-walled cells ; 4, a vascular bundle. 



Fig. 17. Longitudinal section of a fragment of stem of Cattlei/a hiteriiieiUa, from epidermis througli a 



tibro-vascular bundle, X 200. 



1, cuticle epidermal and hypodermal cells ; 2, fundamental tissue of soft thin-walled cells ; 3, a row of short 



thick-wallcd cells with granular protoplasmic contents ; 4, woody fibre ; 5, two contiguous spiral 



vessels ; (i, parenchyma. 



extent the same functions as the leave 

 chlorophyll. 



Ordinary roots contain no 



