SCALARIFORM VESSELS. 25 



like a weed, having pretty buff or pink-coloured flowers, 

 covered with glandular hairs. 



SPIRAL CELLS OF BALSAM. 



These are from the common Balsam of our garden, and 

 show the bundles of long cells made up of spiral fibre, 

 which often break and pass into annular fibre : you may 

 perceive some of these in detached rings. These cells con- 

 tain air, and are those which most resemble the trachea of 

 insects. Those of the Leek are also very remarkable, and 

 the common garden Rhubarb will furnish you with abun- 

 dant specimens. Take a little boiled Rhubarb, and pick it 

 to pieces with a mounted needle in a little water, when bun- 

 dles of spiral vessels will be easily found. 



SPIRAL CELLS^OF SPHAGXUM. 



Sphagnum is a moss growing in marshy places, and its 

 leaf shows a beautiful arrangement of spiral fibres in its 

 large oval cells, whilst in the smaller ones you will see the 

 granules of chlorophylle which colour the leaf. 



SCALARIFORM VESSELS, 



so called because they resemble the steps of a ladder, are 

 peculiar to ferns and to asparagus. They are secondary 

 ideposits on the cell wall, and somewhat of the nature 

 of spiral fibre. Under polarized light they are very beau- 

 tiful. 



When you pull up a common Bracken or Tern, and cut 

 the root across, the brown figure you see, called King 

 Charles in the Oak, is made up of these scalariform vessels. 

 They are very troublesome to prepare, but this is the easiest 

 way that I know of : Cut up the root and boil it until 

 tender enough to peel; put the centre part into a jam- 

 pot with water and a little nitric acid; let it stand in 

 boiling water for some hours, then pick the long white 

 fibres carefully out, wash them in boiling water over and 



