Page:Popular Science Monthly Volume 69.djvu/217

Rh In Mr. Burbank's cross of the English walnut (Juglans regia) with the California walnut (Juglans Californica) the first generation shows a certain blending of the traits of one species with those of the other. In the next generation appears every conceivable kind of variation in every feature of the plant and in every function of its organs.

The last sentence offers a fair example of the misrepresentation to which Mr. Burbank's horticultural work has been so profusely the object. A similar progeny of a hybrid oak is included in experimental cultures in New York, and the observer may readily see that the physiological possibilities are not exhausted in either case. To illustrate the possible variations in form would require many millions of individuals, as may be seen when a simple computation shows that seven single differentiations would require more than sixteen thousand individuals for their exemplification, if the characters behaved as indivisible units. If, however, qualities or characters are capable of modification or variation, as indicated by the quotation, the number of different forms of any organ of the entire plant would be so large as to make estimates useless. Then again by what extended experimentation have the conceivable variations in every function been ascertained?

A wider range of literary license prevails in some recent articles by Mr. E. A. Ortmann. Among other inaccuracies he says:

De Vries failed entirely to take notice of this fundamental principle (intergradation), and to show that his elementary species and his mutations are not connected by intermediate forms.

Although somewhat familiar with 'Die Mutationstheorie' and 'Species and Varieties,' no explanation occurs to me to account for this mistaken statement. A few combination forms were found and faithfully recorded by de Tries, but these were certainly not intergrades, whatever might be said of them.

Mr. Ortmann's discussions introduce a novel feature, in his estimate of the futility of experimental methods, which has the sole merit of boldness, coming at a time when the greater number of workers in the subject are turning from discussions and statements of opinion to actual observations. A mistrust is shown by him of experiments 'under artificial and unnatural conditions, as for instance in the botanical garden, or with domesticated forms.' Several months ago the following characterization of this attitude was given in a paper on the subject:

Popular belief in the influence of environment and the inheritance of acquired characters finds its commonest expression in 'that plants have been changed by cultivation.' Domesticated races are spoken of as 'garden forms' by botanists and horticulturists, with the implication that they are specialized types resulting from the effects of tillage. Now so far as actual cultivation is concerned, this assumption is without foundation, since at the present time