THE SPERMAPHYTES. 209 



4. Study the female flowers. These are borne near the 

 very tip of the new shoot as pinkish-green cones. They 

 are to be gathered in June. Are these cones sessile, or 

 borne on stalks ? Draw a cone. Dissect a cone. Notice 

 that the modified leaves are of two kinds. The thin and 

 small scale leaf or bract corresponds to an ordinary leaf ; 

 the thicker scale or carpel bears ovules. Draw a bract. 

 Where on the carpel are the ovules situated ? Draw a 

 carpel, showing the ovules. The ridgelike projection of 

 the carpel is called the keel; its function is to guide the 

 pollen grains towards the ovules. 



5. Study the development of the ovule into the seed. 

 Two years are required for this. Branches of Scotch, 

 Austrian, or Red Pine may be found in the early part of 

 the summer bearing the cones at three stages of develop- 

 ment : a. The female flowers, already studied, at the apex 

 of the new shoot, b. Cones one year old at the apex of 

 the shoot of the preceding year. c. Cones in the second 

 year of their growth at the apex of the two-years-old 

 shoot. 



What is the position of the ovules on the carpels of the 

 youngest cone ? Find on each ovule the micropyle a 

 small opening into the interior through which the pollen 

 tube enters. Where on the ovule is it situated ? Make a 

 section of an ovule through the micropyle ; with a hand 

 magnifier or low power distinguish the integument or 

 outer coat ; next within the integument is the nucellua, 

 composed of parenchyma ; near the end of this mass of 

 parenchyma farthest away from the micropyle is situated 

 the embryo sac, which is a large cell containing more or 

 less of a very soft tissue the endosperm. Draw. 



Dissect a year-old cone. Make a section of a seed 

 through the micropyle. Compare the micropyle, integu- 

 ment, embryo sac, and its contents with the same parts in 

 the youngest cone. Draw. 

 CLARK'S EOT. 14 



