Structure, etc., of Epiphegus Virginiana. 381 



In immature ovaries, there is a.considerable empty space 

 in the centre of the cavity. In later stages the ovules have so 

 enlarged as to entirely fill the ovary. They lie in a uniform 

 structureless, faintly stained matrix. Starch is quite abun- 

 dant in the walls of the young ovary, and gradually increases 

 in amount in older ovaries. But in the mature capsule there 

 is relatively little present. It has probably been used up in 

 the growth of the ovules. 



As the ovules grow and fill up the cavity, a considerable 

 tension is brought to bear on the walls of the ovary. The 

 outer cells of this wall assume a stretched-out, flattened 

 appearance, and frequently are torn completely away. This 

 tension produces the vertical split that occurs lengthwise 

 across the summit of the ovary. In a still later stage, the 

 entire tissue of the ovarian wall has assumed a stretched-out 

 appearance. But the inner cells of the wall, on each side of 

 the longitudinal split across the capsule, have enormously 

 enlarged and become crowded with starch grains. Very 

 little starch is now present elsewhere in the ovary. Now the 

 action of the valves in dehiscing is to pull apart and curl 

 their edges outward and downward. And the downward 

 pull of the stretched ovarian wall, together with the out- 

 ward growth of the two swollen cushions along the split 

 edges, would produce this rolling of the valves outward and 

 downward. 



The Nectary. — This is present alike in the cleistogamic 

 and the evident flowers. It is generally similar in each, but 

 is somewhat smaller in the cleistogamic flower, especially 

 so in somewhat later stages. It appears as a swelling on one 

 side of the ovary, antero-laterally in position just above the 

 base (Fig. 5). Neither its depth nor its thickness is very 

 great, but it has considerable length, running half-way 

 round the ovary in chasmogamic flowers. It is not so long 

 on the cleistogamic ovary. 



The nectary consists of a kind of tissue, strikingly unlike 

 the surrounding cells in general appearance. It consists of 



