December, 1910,] 



537 



Miscellaneous, 



fundamental idea that they are large 

 and permanent variations, breeders and 

 gardeners in general attach three other 

 ideas, namely, that high nutrition and 

 other extreme conditions favour sport- 

 ing ; that many plants must be culti- 

 vated a long time before sporting is 

 induced, and that in any case sports are 

 actually or relatively very rare. Will 

 these ideas stand the test of scientific 

 scrutiny experiments? It is evident 

 that these problems are of high import- 

 ance both to evolutionists and agricul- 

 turists. De Vries with his Oenotheras 

 and his theory of mutation as the chief 

 factor in evolution, has particularly 

 interested the scientific world in these 

 phenomena. He has worked out ia great 

 detail the fact9 of variation as they 

 occur in the evening primrose and makes 

 a strong case for his theory. Recent 

 cytological study of the Oenothera 

 mutants or variants shows that one of 

 them has twice a9 many chromosomes 

 as the others ; in other words, that this 

 mutant at least has suffered a pronounced 

 change in the hereditary mechanism. 

 It is only natural that would at once 

 have aroused the suggestion that per- 

 haps all sports or mutants are the result 

 of more or less marked derangement of 

 the hereditary mechanism, by which a 

 character or iactor of some sort is gained 

 or lost. MacDougal's work in subjecting 

 very young ovules to chemical influences, 

 and Gagers similar experiments with 

 radium emanations, are also reported to 

 have yielded marked variations, perhaps 

 sports. Tower also secured true sports 

 in increased number from his Colorado 

 potato beetles by subjecting them to 

 untoward conditions of heat and mois- 

 ture during breeding. In this case, 

 however, all the sport secured were 

 previously found occurring naturally. 

 There is a tempting subject here for 

 speculation — indeed one that has been 

 assiduously tilled, but to follow it up 

 will lead us too far afield. The 

 limited historical and experimental evi- 

 dence of a critical character clearly up- 

 holds, however, the reality of sports. 



It is an illuminating fact that most of 

 the information concerning the origin of 

 cultivated plants and animals is that 

 brought together long ago by Darwin. 

 Recently De Vries has gathered much 

 additional data. Both these men sought 

 the facts primarily in support of a theory. 

 Scientific men are usually more concern- 

 ed in finding an explanation of pheno- 

 mena than in gathering the facts. But 

 we cannot all be philosophers and theo- 

 rists—indeed, the principal difficulty 

 with biological science is that we have a 

 plethora of theory and a dearth of critical 

 68 



facts. Especially is this true in the sub- 

 ject of biological evolution, where nearly 

 every possible guess as to actual methods 

 of evolution has been made. Where 

 such guesses or theories stimulate addi- 

 tional inquiry they are valuable — other- 

 wise, they are useful only to practise 

 mental gymnastics. It is the great merit 

 of many recent investigators, De Vries in 

 particular, that they emphasize the im- 

 portance of experimentation. De Vrie's 

 work bristles with suggestive lines of 

 experimentation mostly bearing on the 

 subject of the origin of cultivated plants, 

 and nearly all of practical importance 

 in agriculture as well as of great interest 

 in themselves. If any one believes that 

 there is any immediate likelihood of 

 biologists agreeing on evolution, all he 

 has to do, using the slang of the day, is 

 to start something. However much 

 agreement there may be on the facts — ■ 

 there is sure to be violent disagreement 

 on the interpretation of the facts. For 

 example, De Vries and others believe 

 that sports which usually breed true 

 from the start are intrinsically different 

 from ordinary or fluctuating variations 

 induced by soil or otherwise, and which 

 have no effect on the offspring. On the 

 other hand. Tower, who has conducted 

 extensive investigations in the evo- 

 lution of the Colorado potato beetle and 

 its I'elations — work comparable to that 

 of De Vries on Oenothera — argues strong- 

 ly 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 

 characters in large part at least tem- 

 porarily. 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 trans- 

 mitted 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 charac- 

 ters limited in both amount and duration. 

 Are they then fluctuations or mutations ? 

 Those who hold that fluctuations have 

 no effect at all on heredity, suggest that 

 the sugar beet and kindred cases may 

 represent complex polyhybrids con- 

 tinually breaking up, and that rigid 

 selection would, therefore; result in 

 securing pure constant lines with sugar 

 content. Many mutations are at first 



