2O0 PART II. VEGETABLE HISTOLOGY. 



Beautiful differential staining may also be produced by placing the sections 

 as soon as cut, in Hanstein's Rosanilin Violet, and letting them remain a short 

 time, or until sufficiently stained. They may then be anhydrated and mounted 

 in balsam, as directed above, or without anhydration they may be mounted in 

 glycerin jelly. 



After the structure and arrangement of the tissues and tissue systems of 

 this stem are well understood, similar studies, for the sake of comparison, should 

 be made of twigs of the Bass-wood, Apple, Maple, Witch Hazel, or other com- 

 mon woody plants, and the resemblances and differences of structure carefully 

 noted and described by the aid of drawings. 



The stems of several herbaceous Dicotyledons, such as those of the Begonia, 

 Buckwheat, Datura, Cow Parsnip and Common Milkweed, should now be 

 studied in the same way. 



Make similar studies, also, of the stems of aquatic Dicotyledons, such as 

 the Water Chinquepin, the White Water-lily, the Yellow Water-lily, etc. 



In what respects do the fibro-vascular bundles of the above-named stems 

 of herbs and aquatics differ from those of the woody stems you have studied ? 



2. For the study of bi-collateral bundles, make thin sections of stems of 

 the Pumpkin, Squash or common Watermelon, and study them in a similar 

 manner. Compare these with sections of the stem of the Yellow Dock. 



3. For the study of the Monocotyledon type of stem structure, first make 

 thin sections of the stalk of the common field Corn, treating the sections in the 

 same way as it was directed to treat those of Menispermum. Note the distribu- 

 tion of the bundles, and then study their structure, the relative arrangement of 

 xylem and phloem, the tissues composing each, and determine whether or not 

 they are separated from each other by a cambium area ; study what tissues of 

 the stem are lignified, and what ones unlignified, and note the tissues of the 

 hypoderma, observing whether they are fibrous or not, the extent to which their 

 walls are thickened, etc. 



Now compare with this, sections of the stems of other herbaceous Mono- 

 cotyledons, such as the Spiderwort, Canada Lily, Tuberose, and Wheat. 



Compare, also, sections of the stem of a woody Monocotyledon, as that of 

 Smilax or Rattan, and note carefully the structural differences. 



Lastly, compare sections of aquatic Monocotyledons, such as Pickerel 

 Weed, Bulrush, and Calamus. 



4. For the study of the concentric bundle and the Fern type of stem, 

 make similar studies of the rhizome of Pteris aquilina, of Aspidium marginale, 

 and of Polypodium vulgare. 



5. For the study of radial bundles and root structure, first make sections 

 of the rootlets of the Sweet Flag or Calamus, or of the Virginia Spiderwort, 

 preparing sections as before. Identify the xylem rays and the alternating 

 phloem masses ; determine the number of each, and the tissues which compose 

 them. Identify the pericambium zone and the endodermis, and study the 

 character of the cells which compose each of them. 



With these, compare sections of the roots of other Monocotyledons, such as 

 those of Indian Corn, Amaryllis, Indian Turnip and Calla, making drawings 

 and descriptions of the central fibro-vascular bundles in each case. 



