82 Variation 



or two exceptions. A few lots showed a perfect uniformity in regard 

 to all the stalks and ears: these were small families. This fact 

 suggested the idea that each might have been derived from a single 

 ear. During the selection in the previous summer, Nilsson had tried 

 to find as many ears as possible of each new type which he recognised 

 in his fields. But the variability of his crops was so great, that 

 he was rarely able to include more than two or three ears in the 

 same group, and, in a few cases, he found only one representative 

 of the supposed type. It might, therefore, be possible that those 

 small uniform plots were the direct progeny of ears, the grains of 

 which had not been mixed with those from other ears before sowing. 

 Exact records had, of course, been kept of the chosen samples, 

 and the number of ears had been noted in each case. It was, there- 

 fore, possible to answer the question and it was found that those 

 plots alone were uniform on which the kernels of one single ear 

 only had been sown. Nilsson concluded that the mixture of two or 

 more ears in a single sowing might be the cause of the lack of uni- 

 formity in the progeny. Apparently similar ears might be different 

 in their progeny. 



Once discovered, this fact was elevated to the rank of a leading 

 principle and tested on as large a scale as possible. The fields were 

 again carefully investigated and every single ear, which showed a 

 distinct divergence from the main type in one character or another, 

 was selected. A thousand samples were chosen, but this time 

 each sample consisted of one ear only. Next year, the result 

 corresponded to the expectation. Uniformity prevailed almost every- 

 where ; only a few lots showed a discrepancy, which might be 

 ascribed to the accidental selection of hybrid ears. It was now clear 

 that the progeny of single ears was, as a rule, pure, whereas that of 

 mixed ears was impure. The single-ear selection or single-ear sowing, 

 which had fallen into discredit in Germany and elsewhere in Europe, 

 was rediscovered. It proved to be the only trustworthy principle of 

 selection. Once isolated, such single-parent races are constant 

 from seed and remain true to their type. No further selection is 

 needed ; they have simply to be multiplied and their real value 

 tested. 



Patrick Shirreft', in his early experiments, Le Couteur, Hays and 

 others had observed the rare occurrence of exceptionally good 

 yielders and the value of their isolation to the agriculturist. The 

 possibility of error in the choice of such striking specimens and the 

 necessity of judging their value by their progeny were also known to 

 these investigators, but they had not the slightest idea of all the 

 possibilities suggested by their principle. Nilsson, who is a botanist 

 as well as an agriculturist, discovered that, besides these exception- 



