GENERAL BIOLOGY 



III. GERMINATION. 



In young seedlings grown in moist blotting paper observe : 



1. The expanding Cotyledons. Color? 



2. The branching Root which has grown out from the apex of 

 the hypocotyl. 



a Mount a small branch of a root in water and examine under 

 the low power. Observe the delicate root hairs standing at right 

 angles with the rootlet. On what portion of the rootlet are they 

 most abundant? 



3. The smooth round stem (hypocotyl) lying between the Coty- 

 ledons and the root. 



4. Between the Cotyledons is the expanding plumule, showing 

 the primary leaves and the bud between them. 



Draw a germinating plant to show all of these parts. 



IV. SEEDLINGS. (1-2 weeks old.) 



Carefully dig up a seedling 1-2 weeks old and observe: 



1. The cotyledons lifted above the soil by the growth of the 

 hypocotyl. Test portions of a cotyledon for starch and dextrose. 

 What is the significance of their withering during the growth of 

 the plant? 



2. The branching roots which anchor the plant in the soil. Ob- 

 serve particles of soil attached to the root hairs. Do roots ever 

 grow from any portions of the stem except the extreme lower end? 



3. The heart-shaped primary leaves with long stalk (petiole) 

 attached to opposite sides of the stem. At its distal end the petiole 

 expands into the blade with three main veins, each of which 

 branches repeatedly, thus giving rise to a net-veined leaf charac- 

 teristic of Dicotyledons (Exogens). On each side of the petiole, 

 near the base of the blade, is a rudimentary leaflet, the stipel, and 

 on each side of the base of the petiole is a small leaf, the stipulei. 



4. At the apex of the stem is the bud from which the central 

 axis of the plant will develop, and a similar bud occurs in the axil 

 (upper angle between leaf and stem) of every leaf. 



Draw a seedling showing all of these parts. 



V. MATURE PLANT (8-10 weeks old). 

 (A). Vegetative Organs. Gross Anatomy. 



In a mature plant observe : 



I. The further development of the root system. Root tubercles 



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