84 MICROSCOPICAL RESEARCH 



PLATE VII. 



STEM STRUCTUEE. 



Fig. 23. Transverse section through resin passage. Stem of Pine 

 X 75 dia. Tissue fixed as above. 1. Primary ground tissue. 

 2. Thickening band of prosenchyma. 3. Secreting cells of 

 canal. 



Fig. 24. Transverse section. Old Wood of Pine x 35 dia. Cut ^/looo in- 

 Unstained. 1. Spring growth of the wood. 2. Autumn 

 and winter growth. 3. Resin canal. 4. Medullary ray. 



Fig. 25. Radial longitudinal section. Old Wood of Pine x 75 dia. 

 Cut i/ioooiii- Unstained. 1. Bordered pits in surf ace view. 

 2. Medullary ray in radial view. 3. Cell-wall in radial 

 view. 



Fig. 26. Tangential longitudinal section. Old Wood of Pine x 75 dia. 

 Cut 1/ 1500 in. 1. Bordered pits in transverse section. 

 2. Medullary ray in section. 3. Cell-wall in tangential 

 view. 



