ON REVERSIBLE TRANSFORMABILITY OF 

 ALLELOMORPHS 



H. TERAO 



The Imperial Agricultural Experiment Station, Tokyo, Japan 



In genetical studies of variegation in plants, the fact 

 has been observed occasionally that with a certain fre- 

 quency a dominant allelomorph occurs in the correspond- 

 ing recessive homozygote (De Vries,^ Correns,^ and 

 Emerson^). In this paper the author presents a new in- 

 stance of a similar phenomenon, which it is hoped may 

 throw additional light on the subject. 



In certain pedigree cultures of the rice plant, Oryza 

 sativa L., there happened to occur in 1912 families con- 

 taining besides ordinary fertile plants a number of sterile 

 plants. These sterile plants were normal in their growth, 

 but showed a considerable barrenness at the ripening 

 season. Some of them yielded no seed whatsoever, others 

 bore a small number of normal seeds, and very few were 

 mosaic forms with higher fertility. These families, two 

 in number, each belonging to a different variety, were 

 derived from single plants of the fonner generation, and 

 were very uniform in other characters. From them the 

 experiment was started. 



The rice plant, being a self-pollinated species, is con- 

 venient material for breeding experiments. Although 

 the experiments in this investigation were made largely 

 from open-pollinations, the results obtained were always 

 similar to those from experiments in which plants were 

 artificially protected against accidental natural crossing. 



The observations of 1912 and 1913 are shown in sum- 

 marized form in Tables I and II, a and b, and point to the 

 following conclusions. Sterility behaves as a simple re- 



iDe Vries, H., "Die Mutationatheorie, " Bd. I, 1901, pp. 489-^11; 

 "Species and Varieties, their Origin by Mutation," 1905, pp. 309-339. 



2Correns, C, Berichte der Deutschen Botanischen Gesellschaft, Bd. 28, 

 1910, pp. 418-434. 



3 Emerson, R. A., American Naturalist, Vol. 48, 1914, pp. 87-115; 

 Genetics, Vol. 2, 1917, pp. 1-35. 



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