WALL STRUCTURE IN THICK CELL WALLS 



137 



conception of structure in these cells is therefore to be represented as in 

 Fig. 51. This structure has now been fully confirmed in the electron 

 microscope (41 (<^)). 



Passing finally to the third cell type whose structure has now been 

 worked out in sufiicient detail, corresponding investigations were 

 carried out in the writer's laboratory by Dr. K. Singh, of the Forest 

 Research Institute at Dehra Dun, India, on samples of bamboo kindly 



^ 



Fig. 52. For explanation, see text. 



provided by the Institute. The bulk of the work was performed on the 

 species Dendrocalamus strictus but the observations have mostly been 

 corroborated with other species also (D. longispathus, Bambusa poly- 

 morpha, B. arundinacea, Melocanna bambusoide, and Neuhouzea 

 Dullod). These fibres, like sisal, are monocotyledonous but, unlike any 

 of the cells studied up till now, they develop from the same ground 

 meristem as parenchyma cells, so that they form an interesting contrast. 

 The problem involved is, however, a much more diSicult one. The 

 fibres cannot be obtained in the immature condition, as could the fibres 

 of sisal, and they are arranged in much too haphazard a fashion to 

 allow the use of the method found so satisfactory for tracheids and 

 wood fibres. Recourse has thus to be made to a thorough optical 

 analysis. 



