GOSSYPIUM 443 



to be simultaneous. After the formation of the endosperm nucleus, 

 free nuclear divisions occur until there may be from twenty to 

 twenty-five endosperm nuclei in the embryo sac. Wall formation 

 is initiated at the micropylar end of the embryo sac, and finally a 

 massive endosperm is produced, which is later resorbed by the 

 embryo until only one layer remains. 



Embryogeny. — The development of the cotton embryo has been 

 described by Reeves and Beasley (x8). The first division of the 

 zygote, which usually occurs the second day after fertilization, 

 is transverse; and this is followed by a vertical division of the 

 apical cell and occasionally of the basal cell. A short suspensor is 

 formed, but it apparently disintegrates early in ontogeny; and 

 Balls' (3) statement that there is no suspensor may be explained by 

 this fact. The two apical cells divide to form a quadrant, and from 

 this the eight-celled embryo arises about the fourth day. Divisions 

 of each of the eight cells result in a sixteen-celled embryo that is 

 usually five-tiered. 



The initial stages occur before there is any appreciable increase 

 in the size of the embryo; and in about nine days, the cotyledons 

 and hypocotyl are differentiated. This is followed by a period of 

 rapid growth so that in twelve to fifteen days provascular strands 

 develop, and the palisade cells differentiate in the cotyledons. At 

 about this time, the resin glands appear, being formed lysigenously 

 from two or three cells. By the eighteenth day or before, oil, 

 starch, pentosans, gossypol and proteins are present in the embryo. 

 During the closing periods of growth, the embryo continues to 

 increase in weight until about the thirty-fifth day, when it begins 

 to lose weight by desiccation, reaching an approximate equilibrium 

 by the forty-third to forty-seventh day. 



Development of the Fiber. — The development of the fiber has 

 been described by Balls (5), Hawkins and Serviss (ii), Gulati (19), 

 Singh (19), and Farr (14, 15, 16); and, recently, its structure has 

 been investigated by Kerr (xi), Anderson and Moore (i), and 

 Anderson and Kerr (i). 



The ontogeny of the fiber may be divided into two phases, the 

 first dealing with its initiation and elongation; and the second 

 with the thickening of its wall. The epidermal cells nearest the 

 chalazal end of the ovule are the first to develop and produce the 

 longest fibers, while those at the micropylar end arise later or may 

 fail to develop at all. On the day of flowering, the individual 



