1919] FIELD CROPS. 437 



1). — In this paper, a coutributiou from the Bureau of Plant Industry, U. S. 

 Department of Agriculture, the author describes observations made on hybrids 

 derived largely from a cross between Florida teosinte and Tom Thumb popcorn 

 in an effort to throw some light on the morphology of the maize ear, together 

 with a possible explanation of its evolution. Six Fi plants were grown, and 

 from the self-fertilized seed of one of these 127 F2 plants were produced. Sev- 

 eral hundred Fa plants from open pollinated seed were also examined. 



In order to make a detailed comparison of the pistillate inflorescences of Zea 

 and Euchlsena, it was deemed necessary to recognize as a morphological unit 

 the organs borne by a single metamer of the rachis, this unit being designated 

 as an alicole. The single spikelets, two-i-anked alicoles, and separate alicoles 

 of the pistillate inflorescence of Euchlfena were then contrasted with the paired 

 spikelets, many-ranked alicoles, and yoked alicoles of the pistillate inflorescence 

 of Zea. The stages between the Euchlsena spike and the Zea ear as observed 

 in hybrids between the two genera are summarized as follows : 



" The suppressed pedicelled spikelet in each alicole reappears. The alicoles 

 become more crowded and their number is increased. The alicoles associate 

 themselves in pairs or yokes. The axis twists, increasing the row of ali- 

 coles. The order in which these changes occur is by no means fixed, but taken 

 together they comprise all the changes necessary in deriving the maize ear 

 from the Euchlsena spike. 



" In this series of intermediate stages nothing was observed that affords sup- 

 port for either the fasciation or * reduced branch ' theory of ear formation. 

 There is also evidence from the maize ear itself that the association of alicoles 

 into pairs is more fundamental than the linear arrangement. 



" In all the hybrids between maize and Euchlsena that have been observed 

 there has appeared no suggestion of either pod corn or Zea ranwsa. Since it 

 can scarcely be doubted that the peculiar characteristics of both of these muta- 

 tions represent the reappearance of ancestral characters common to the An- 

 dropogonese, it would seem that in crossing maize and Euchlsena, and thus call- 

 ing forth a series of intermediate forms, we are not returning to the point in 

 the ancestry of maize where it became differentiated from the Andropogonese. 

 Furthermore, if the stages shown in the hybrid plants were to be taken as 

 indicating the path of evolution of the ear, it would be necessary to assume 

 that the central spike of the stamina te inflorescence or tassel had evolved 

 separately and along different lines. The close homology between the ear and 

 the central spike of the tassel makes such an assumption unreasonable. 



" In the present article emphasis has been placed on the shortening and twist- 

 ing of the axis of a single spike as a possible method of deriving a structure 

 like the maize ear from the inflorescence of Euchlfena. This has been done, not 

 because the method is believed to represent the most probable course of evolu- 

 tion, but because the present discussion has been restricted to the evidence 

 afforded by hybrids of maize and Euchlfena, which seems to require such an 

 interpretation. Facts of other kinds are more easily interpreted by the theories 

 of fasciation and reduction of branches, but there are also facts that do not 

 seem to accord with any of the theories yet proposed. Until the ' apparently 

 contradictory evidence can be reconciled, it seems best to keep the several pos- 

 sibilities in mind and await additional evidence before attempting a complete 

 interpretation." 



Inheritance of waxy endosperm in maize, J. H. Kempton (U. S. Dept. Agr. 

 Bui. 75Jt {1919), pp. 99, fl{)s. 7//).— This bulletin describes the results of investi- 

 gations begun in 1910 in a further effort to study the correlation between 

 endosperm texture and the color of the aleurone. A series of crosses were 

 made between the white Chinese variety of corn having waxy endosperm 



