MAIZE— KEMPTON 397 



most (pi. 17, fig. 2). These brandies are borne in a two-ranked or 

 distichous arrangement. Each branch beginning with the uppermost 

 and descending has one less node than the one next below. In plants 

 not so well grown the internodes of these branches often do not 

 elongate, thus leaving the entire branch structure enclosed in the 

 sheaths much as the husks enclose the ear of maize. In these cases 

 the number of sheaths is that corresponding to the position of the 

 branch on the main axis. 



In most types of corn there are no buds in the axils of the leaves 

 above the ear and the ear is borne in the axil of the fifth or sixth leaf 

 from the top, a position that in teosinte would give a branch with 

 seven or eight nodes. If, therefore, the ear of corn has come about 

 through the telescoping or shortening of a branch at this position the 

 ear should be enclosed in seven or eight husks. Actually in most 

 commercial varieties the husk covering is much greater than this. 

 Either several nodes above the ear have been lost or extra nodes have 

 been intercalated on the ear branch. 



The terminal panicle of maize, or the tassel, is characterized by 

 having the branching region well defined \vith branches borne more or 

 less at right angles from the axis, and the panicle terminates in an 

 erect organ known as the central spike. In maize this organ is a con- 

 tinuation of the axis of the panicle or rachis and is covered with paired 

 spikelets arranged in eight or more rows (pi. 19). 



In teosinte and in gama grass the rachis does not continue beyond 

 the branching region, and the panicle terminates in a branch in no 

 wise differing from all the other branches (pi. 18). On it, as on all 

 the other branches, the spikelets are in four rows, i. e., two rows of 

 paired spikelets. 



The tassel of corn with the central spike removed would be similar 

 to the tassel of teosinte. It was early realized that the ear of corn 

 was the homologue of the central spike of the tassel and there is no 

 disagreement on this score. The ear is envisioned as having arisen 

 through a transformation of male into female spikelets with the sup- 

 pression of one flower in each spikelet, loss of the lateral branches, and 

 shortening of the internodes. By tliis means an ear of corn could 

 be derived from the terminal panicle of a lateral branch (pis. 20 and 

 21). 



Although this picture of how the ear could be derived from a corn 

 tassel is satisfactory, it fails to take into account that the organ of 

 the tassel — the central spike — from which the ear is to be derived is 

 as much in need of an explanation as the ear itself. The problem of 

 the origin of the ear thus becomes the problem of the origin of the 

 central spike of the tassel. 



The earliest explanation suggested for the origin of the ear was 

 that it came about through a fusion or fasciation of the branches of 



