376 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1911. 



glove plants appear to afford us reliable evidence in favor of the idea, 

 that under certain unknown conditions the flowers of a wild plant 

 may become suddenly and completely altered in character, and that 

 variations of tins description are passed on from one to succeeding 

 generations by means of the germ cells. 1 



From a packet of Fox-glove seeds (Digitalis purpurea) sown in the 

 year 1906, 54 plants were, in June, 1907, planted in a shrubbery of fir 

 trees with an undergrowth of laurels. Of these plants, 51 grew into 

 normal Fox-gloves, but the 3 remaining plants were sports, which 

 we may distinguish by the letters A, B, and C. 



A. In this plant the flowers of the lower half of the stem possessed 

 only a bifid upper petal and seven stamens united at their bases. 

 The flowers of the upper part of the spike were normal. 



B. A fine, well-grown plant 4£ feet high; throughout the whole 

 length of the spike the flowers consisted of a bifid upper petal, seven 

 stamens, and style. The upper part of this spike was isolated; it 

 produced abundant self-fertilized seed. 



C. The spike of this plant grew to be 5 feet high; from base to apex 

 its flowers consisted of nine stamens and a style, with no vestige of 

 petals. 



It is unnecessary to follow the history of plant A, as it was only the 

 lower part of the spike in which the flowers were abnormal, and the 

 stem was not isolated. 



Seed taken from the upper covered part of the plant B, whose 

 flowers consisted of a bifid petal, 7 stamens, and a style, germi- 

 nated abundantly; 21 of these plants flowered in 1909. Thirteen of 

 these 21 plants produced spikes of the parent type, and 8 of the 21 

 plants produced normal Fox-glove flowers. One of the 13 plants 

 grew to be 5 feet 1 inch high, its spike producing 1 bifid petal and a 

 style; but its terminal flower consisted of 22 stamens and a large 

 flask-shaped carpel (divided into 7 compartments) and style, but 

 having no corolla; that is, it had no petals. (As shown in photograph 

 exhibited.) 



The season of 1909 was sunless, with constant ram; consequently, 

 all covered plants suffered much from mildew, but I managed to col- 

 lect some self-fertilized seed from the terminal flower of the plant 

 referred to, and this seed germinated and flowered in 1911. Every 

 one of the 12 plants I reared from the seed of the terminal flower pro- 

 duced flowers precisely like the parent. Two of these plants were 

 isolated and their self-fertilized seed germinated freely (September, 

 1911). 



The seed originally collected from the covered part of plant C 

 of 1907 had produced plants which, in 1909, gave flowers precisely 



1 N. C Macnamara, on Mutations in Fox-glove Plants. Linnean Society of London, General Meeting 

 Nov. 16, 1911. 



