June 10, 1910] 



SCIENCE 



895 



tions in the evolution of the Colorado 

 potato beetle and its relations — work com- 

 parable to that of De Vries on (Enothera 

 —argues strongly to show that his sports 

 or mutations differ from fluctuations only 

 in degree, not in kind. By definition, if 

 the variant transmits its characters fully 

 it is a mutation or sport; if not at all, it 

 is a fluctuation. But many supposedly 

 fluctuating variants transmit their char- 

 acters in large part at least temporarily. 

 Thus peas grown on warm or sandy soils 

 are said to become mature earlier than the 

 same variety planted on colder soils— and 

 this difference is transmitted at least to 

 their immediate progeny. It is believed 

 to be in virtue of this supposed type of 

 variation that northern grown seeds like 

 corn often possess increased earliness when 

 planted south; that continued selection as 

 in sugar beets is necessitated to keep the 

 plants to a high standard. Such plants 

 clearly transmit to their progeny char- 

 acters limited in both amount and dura- 

 tion. Are they then fluctuations or muta- 

 tions? Those who hold that fluctuations 

 have no effect at all on heredity, suggest 

 that the sugar beet and kindred cases may 

 represent complex polyhybrids continually 

 breaking up and that rigid selection 

 would, therefore, result in securing pure 

 constant lines with high sugar content. 

 Many mutations are at first partial, as in 

 the cases of many double flowers. The first 

 suggestion of doubling is often only a single 

 additional petal. In the progeny of this in- 

 dividual some with more petals nearly al- 

 ways occur— and the process eventually 

 results in full doubling. The general 

 progress in these cases is seemingly par- 

 allel to what occurs in securing the pure 

 lines out of a complex hybrid. A similar 

 ease if true is found in Burbank's red 

 Eschscholtzia — the first hint of which was 

 a red streak in the petals of a yellow sort. 



By continued selection the pure red was 

 isolated. Professor Setehell tells me, 

 however, that red-flowered eschscholtzias 

 occur wild in certain localities in California. 

 There is room for much discussion on all 

 these points— but their settlement re- 

 quires a larger body of critical facts than 

 are yet available. There are plenty of 

 gardeners' accounts of such phenomena 

 to be had and they are probably true, but 

 they do not possess scientiflc accuracy. 

 Along these lines there is presented an al- 

 luring field of botanical work. 



A clearer understanding of the different 

 types or degrees of variation is most im- 

 portant. De Vries would recognize only 

 three types, namely, fluctuations, muta- 

 tions and ever-sporting plants. The 

 latter include mostly plants with varie- 

 gated leaves or flowers— which also con- 

 stantly bear part of their leaves or flowers 

 without variegation. A common example 

 is the variegated-flowered larkspur. The 

 azaleas with flowers on some branches red, 

 on others white or striped, ofl'er perhaps a 

 similar phenomenon. 



It is quite certain that such a elassiflca- 

 tion simplifies the matter too much. 

 Johannsen's work with beans clearly 

 shows that mutations are often very small, 

 even minute— but they are inherited— 

 while similar variations not inherited are 

 considered fluctuations. 



De Vries 's compilation of available evi- 

 dence on the origin of plant sports tends 

 to uphold in general the idea of the gar- 

 deners — namely, that sports are compara- 

 tively rare; that unusual conditions, 

 especially of nutrition, favor their occur- 

 rence ; and that often a plant must be cul- 

 tivated a long time before it will sport. 

 His evidence further shows that in some 

 cases breeders sought out natural sports 

 —and merely intensified their character- 

 istics by cultivation. Whether De Vries 's 



