226 EXPEBIMJENTS WITH PLANTS 



leaves. Bundles whieli group themselves into a circle 

 in the stem and form a branching network in the 

 leaves, as in the Squash, are characteristic of a 

 great group of plants, the Dicotyledons (plants with 

 two seed-leaves) ; a scattered arrangement .of bundles 

 in the stem, together with a parallel course in the 

 leaves, as seen in the Corn, is characteristic of the 

 great group of Monocotyledons (plants with one 

 seed-leaf) . 



Place a small leafy branch of Oak, Hickory or 

 some other hard wood in the solution, and follow the 

 path of the liquid to the very extremity of the growing 

 tip. At the very tip the wood is in separate bundles, 

 as in the Squash, but as we follow it down toward the 

 older part of the stem the separate bundles very soon 

 coalesce to form a continuous ring of wood (and also 

 of bast). 



Take one of the Squash vines which has stood in 

 the solution for some time, cut it square across, and 

 from the cut surface take (with a sharp razor) sections 

 (thin enough to be translucent but still fairly thick), 

 and place them (without water or cover-glass) on a 

 slide, and examine with the low power of the micro- 

 scope. The fibrous bundles show the wood (i. e., the 

 central portion of each bundle) colored red, with the 

 uncolored bast lying on either side of it. Turning our 

 attention to the wood, we see in it two large openings, 

 the ducts (see Fig. 133) . In tracing the colored fluid 



