MICROSCOPICAL EXAMINATION OF POW&W&jJJSf3&J3Jfa<&-\ 101 



5 1 Bast. 



6 1 Parenchyma. See roots and rhizomes. Contents less plentiful 



and less characteristic. 

 7 1 Woody tissue. 



I 2 Wood cells and tracheids. 



2 2 Medullary rays. 



8 1 Vascular tissue. See roots and rhizomes. 

 9 l Sclerenchyma. See barks. 

 10 1 Pith. Usually present. Variable in amount. 



I 2 Size and form of cells. Rosettes. 



2 2 Cell contents. Mucilage, resin, starch. 



VII. WOODS. SEE WOODY TISSUE OF STEMS. 

 I 1 Wood cells. 



2 1 Ducts. 

 I 2 Size. 



2 2 Number and size of pores. 



3 1 Medullary rays. Important and often diagnostic. Study 

 transverse, tangential and radial sections care- 

 fully. 



VIII. PITH. SEE STEMS. 



V. ILLUSTRATIONS WITH DESCRIPTIONS OF THE MORE COMMON PLANT 



TISSUES 



From the foregoing it will be seen that the fully formed and matured 

 tissues and tissue elements and formed cell-contents, which occur in 

 drugs of vegetable origin and which are recognizable under the com- 

 pound microscope, are comparatively few in number and may be 

 classified as follows: 



I. TISSUES 



1. Epidermal and endodermal. 



2. Hypodermal. 



3. Parenchymatou's tissues. 



4. Tracheids and wood fiber. 



5. Ducts of vascular tissue (bundles). 



6. Cork tissues of all kinds. 



7. Bast tissues. 



8. Sclerenchymatons cells and tissues. 



9. Medullary ray tissues. 



10. Secretory and excretory glands and ducts. 



11. Pollen grains and spores. 



