40 MINUTE MARVELS OF NATURE 



that it is difficult to recognise any trace of the 

 original cell-shape in them. By making a longi- 



ng. 26. A longitudinal section through part of the 

 creeping stem of the bracken fern, showing the 

 vascular tubes embedded in the frond tissue. 



tudinal section, with a sharp razor, through the 

 growing-point of a plant stem, for instance, we 



