74 



Elementary Work in Botany. 



ing. You should daily observe the growing pistils of 

 several plants from the time the corolla falls till the seeds 

 are ripe. At intervals of a few days one 

 of the young fruits should be picked 

 and dissected. If you follow the growth 

 of an almond you will find it has at first 

 two ovules (one for each edge of the car- 

 pellary leaf). Usually one soon dies 

 and the almond ripens but one seed. 

 In the very young acorn there are the 

 beginnings of six seeds (two for each 

 carpel) but only one grows. So also in 

 buckeye usually 

 but one of the six 

 ovules grows. In 

 an early stage of 

 its growth the 

 young buckeye 

 fruit appears as 

 shown in the fig- 

 ure at a. The cross-section c shows 

 the three cells and the vertical sec- 

 tion b shows how the two ovules of 

 each cell grow one above the other. 

 Fig. 54 is a diagramatic section of 

 the condition when the fruit is nearly 

 grown. Five of the ovules grow to be as large as mustard 

 seeds or larger and then stop growing. The sixth one 



a 



Fig. 53 

 pistil of a buckeye, b. 

 Vertical section of the 

 ovary cut in the plane f $, 

 shown at c, which is a 

 cross-section cutting the 

 ovary in the plane d e, as 

 seen in a and b. 



Fig. 54. A diagram showing 

 the one-sided development of the 

 buckeye after it has reached the 

 size of a walnut. The midribs 

 (dorsal sutures) of the carpellary 

 leaves are marked m, and their 

 lines of union (ventral sutures) 

 are marked s. a, b and c are the 

 ovules, two in each cell. The 

 fertile carpel makes about half 

 the pod the lower half in the 

 figure, from s ou the left to s ou 

 the right. 



