14 



manila paper hags before an}^ of the silks hiid appeared, and were 

 opened and pollinated four or five da3'S later, when the pistils had 

 matured. After pollination they were immediateh' rebagged, the 

 bags not being linall}' removed until some ten or fifteen days later, 

 when all the silks were dried up. The pollen in every case was collected 

 l)}'^ inclosing the tassel in a large paper sack, which was removed after 

 the pollen had been discharged. It was found in the course of the 

 work that the pollen retained its vitalit}' for at least two weeks, but 

 no experiments were made to determine the length of time it could be 

 retained in good condition. As an indication of the thoroughness of 

 the methods used, the fact may be cited that in at least seven or eight 

 instances, where ears were bagged and not hand pollinated, no kernels 

 set, showing that impurity is not likelj'^ to result from other i^ollen 

 accidentally getting in when ears were bagged. 



The following is a list of the varieties grown, with notes on their 

 characters, etc. : 



Cuzco OR Pkruvian No. 759. — A soft com {Zea amylacea Sturt.) imported directly 

 from Peru by the Section of Seed and Plant Introduction of this Department. The 

 seeds for the writer's experiments were kindly placed at his disposal by Mr. D. G. 

 Fairchild, special agent, then in charge of that Section. As obtained from Peru, the 

 kernels were of mixed colors, apparently belonging to the same but very unstable 

 and variable race. The majority were dark bluish-black or plumbeous (PI. I, tigs. 3-4), 

 while some were mottled with dark purple and white (PI. I, fig. 5), and others 

 mottled in the same way and with a fuscous or ferruginous pericarp. (PI. I, fig. 6.) 



Cuzco No. 760. — In the Cuzco as imported from Peru there were many opaque 

 white or whitish-yellow grains mixed with the plumbeous and variegated kernels 

 described under the pret-eding number, and these, as they appeared to be distinct 

 from the others, were selected out and given the number 760, under which they were 

 distributed by the Section of Seed and Plant Introduction. (PI. I, figs. 7-8.) 

 A plant from one of these kernels, inbred as described in the following immber, gave 

 variously colored grains, showing that Cuzco No. 759 and 760 are apparently simply 

 different-colored kernels of the same variable race. 



Cuzco 7a. — One ear of Cuzco No. 760 was inbred in the greenhouse at Washing- 

 ton, D. C, in the summer of 1898 (Experiment 7a), and matured thirty-five good 

 kernels, of which eighteen were pure yellowish-white, the saqae as the original 

 kernel planted (PI. I, figs. 7-8), and seventeen purplish, most of them being dark 

 purple. These seeds were planted at Lincoln, Nebr., in 1899, and the pollen from 

 some of them was used in crossing experiments that year. Such plants are distin- 

 guished in the writer's notes and in this paper as Cuzco 7a. 



Hickory King (Zea inderdata Sturt.). — A white dent race with very broad, deep 

 kernels and a small white cob. It is the largest-kerneled race commonly grown 

 in the United States (PI. I, figs. 1-2). The seeds were purchased from Wood & Co., 

 of Virginia, and were supposed to have been produced under control conditions. 

 One ear was carefully inbred in the greenhouse in 1898 and came true to the type 

 of the race. The seed of this inbred ear was grown at Lincoln in 1899, and one 

 car again inbred, which came true to type. In neither of the inbred ears was 

 there any suggestion of impurity, and in none of the ears pollinated naturally in the 

 field was any effect visible suggesting previous crossing with a plumbeous-kerneled 

 race like the Cuzco. This peculiar color is shown as xenia on Hickory King (growTi 

 from this seed), X Cuzco No. 759, in the writer's experiments, la and lb, 10a, etc. 



Some seed of Hickory King purchased from Burpee & Co., of Pennsylvania, and 



