. Bursa bursa-pastoris and Bursa heegeri biotypes and hybrids. Bursa bursa-pastoris; Bursa heegeri; Plant hybridization. BIOTYPES AND HYBRIDS. 29 attenuate lobes, and many other variations, have behaved in many respects as if they were the normal fluctuations of a single biotype. While in cer- tain cases there appeared to be a marked capacity of one or the other ex- treme to transmit its character to its offspring-, the usual result of breeding- any one of these variations was a prog-eny g-iving- ag-ain the whole rang-e of fluctuation, or a considerable portion of it. Time and ag:ain forms wer
. Bursa bursa-pastoris and Bursa heegeri biotypes and hybrids. Bursa bursa-pastoris; Bursa heegeri; Plant hybridization. BIOTYPES AND HYBRIDS. 29 attenuate lobes, and many other variations, have behaved in many respects as if they were the normal fluctuations of a single biotype. While in cer- tain cases there appeared to be a marked capacity of one or the other ex- treme to transmit its character to its offspring-, the usual result of breeding- any one of these variations was a prog-eny g-iving- ag-ain the whole rang-e of fluctuation, or a considerable portion of it. Time and ag:ain forms were picked out so different from their sibs that they were thoug'ht to represent distinct elementary species, but breeding-tests showed that their offspring- return completely to the usual condition of the other related Fig. 20.—Btirsa bursa-pastoris rhomboidea from a family of B. bp. simplex. A half sib of the plant shown in fig. li). Over 100 pedig-reed families, including" more than 15,500 individuals derived from the two plants ( and ), have now been studied, and of these families considerably more than half ranged between forms with very obtuse lobes and others having- greater or less attenuation of the lobes, the extreme developments in the latter direction being- scarcely distinguish- able from pure-bred B. bp. tenuis; 17 of the remaining families, in which no attenuate-lobed element was noted, had been injured by too long crowding. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Shull, George Harrison, 1874-1954. Washington, D. C. , Carnegie Institution of Washington
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