66 



BOTANY. 



to leave but a single tissue, which in many cases is com- 

 posed of only a few spiral ves- 

 sels or tracheids (Fig. 37). In 

 other cases, instead of spiral 

 vessels the bundle may consist 

 of a few fibres of bast; or of 

 elongated, thin-walled cells, 

 which are doubtless to be re- 

 garded as meristem-cells which 

 failed to fully change into one 

 of the ordinary permanent tis- 

 sues: this last is a very com- 

 mon accompaniment of reduced 

 bundles. 



Practical Studies. — (a) Break a 



stem of Indian corn and note with 



the nalced eye tlie tough string-like 



fibro-vascular bundles which run 



through the soft tissues. Examine 



^ in like manner the fibro-vascular 



Fig. 3T.-Terminal portions of bundles of the common door-yaid 

 flbro-vasoular bundles m a leaf, . "^ 



reduced to tracheids and spiral Plantain. 



'''®^^®'^' (J) Make a very thin cross-section 



of the stem of Indian corn and, using the microscope, study the bun- 

 dles carefully by comparing with Fig. 30. In bundles from young 

 stems the fibrous tissue will not show as good a development as in 

 the figure. 



(c) Now make thin longitudinal sections of a bundle in such a man- 

 ner as to have the sections pass through a and i in the figure. This 

 may be done by slicing the stem in a longitudinal radial direction. 

 Study again by comparison with the figure and with the previous 

 specimen. 



(d) Make thin longitudinal sections of a bundle at right angles to 

 the last (by longitudinal tangential sections of the stem). 



(e) Study in like manner the bundles of sugar-cane and asparagus. 

 (/) Study by similar sections the bundles of the young stem of 



the Castor-oil Plant and Red Clover. The latter is very convenient 

 for study, as the uppermost joints will furnish as young bundles as 



