178 CARROLL— ON DEVELOPMENT OF 



VI. The flowers are readily self- and cross-fertilized, and seed was 

 produced by cross-pollination between I. fulva and I. pallida. 



VII. The size of cleistogamous and chasmogamous seed is the same. 

 The number in chasmogamous capsules is four or five; in cleistogamous 

 capsules one to three. 



VIII. Drought, weak light, poor soil, excessive temperatures, 

 toxicity of soil and reduction of leafage inhibit chasmogamous flowers, 

 but cleistogamous flowers may be produced under these conditions. 



IX. There are two views as to the morphology of sepals and petals. 

 According to the first view, there are three sepals and three petals, two 

 of the petals being formed by the fusion of four in pairs. According to 

 the second view, there are four sepals and two lobed petals. 



X. The cleistogamous flower shows all the members that appear in 

 the chasmogamous flowers. The petals and sepals are forced off by 

 the expanding ovary as a cap, resembling in appearance the calyptra 

 of a moss. 



XI. The chasmogamous stamens are coherent, with broad filaments 

 and with ligular appendages which are coherent above the pistil; the 

 cleistogamous stamens are separate, strapshaped, without appendages. 



XII. The development of the pollen is peculiar in the degeneration 

 of plates of sporogenous cells. 



XIII. The cleistogamous stamens have a very small number of 

 pollen grains. An endothecium is formed and dehiscence occurs, but 

 the pollen grains remain in the pollen sacs and send down tubes to the 

 stigma. 



XIV. The nucellus is a single layer of ephemeral cells at the sides 

 and micropylar end; below the embryo sac it is composed of five rows 

 of elongate tracheid-like cells which disappear as the embryo sac en- 

 larges. The mature embryo sac is a long curved structure. 



XV. There are four megaspores, the inner one becoming the 

 embryo- sac. 



XVI. Eight nuclei arise in the embryo sac; three are cut off as 

 antipodal cells, and two as synergids. Antipodals and synergids are 

 ephemeral. 



XVII. The pollen tube branches on entering the embryo-sac, each 

 branch carrying a male nucleus. 



XVIII. The first division of the fertilized egg is transverse, the 

 micropylar cell gives rise to the suspensor, and the lower cell to the 

 major part of the embryo. 



