Febbuaby 1, 1907] 



SCIENCE 



189 



knows that many of our garden forms will 

 come true only when treated in a certain way. 

 These various ways, including everything that 

 comes under the head of gardener's 'tricks,' 

 are familiar to the professional and amateur," 

 and their results are regarded among laymen 

 as due to a 'lucky hand.' Pure strains of 

 seed, of course, obtained by pedigree-culture, 

 are the first condition, but pedigree-culture is 

 not all of the secret, since the proper handling 

 of the seeds is also material, as well as the 

 observation of certain ' tricks ' with the grow- 

 ing plants, which have no other oiject hut to 

 furnish the congenial environment to the 

 ohject. 



I think that any one who has ever done ac- 

 tual garden work, trying to raise particular 

 strains of flowers or vegetables, will under- 

 stand what I mean by these 'tricks.' This 

 essential element is obviously lacking in de 

 Vries's experiments: he uniformly bred all 

 his mutants ' in the botanical garden,' and 

 'in well-manured soil,' and apparently also 

 under the same conditions of climate, season, 

 subsoil, insolation, etc., that is to say, under 

 a uniform set of ecological conditions, such 

 as are generally found in a botanical garden. 

 Indeed, it has been questioned that a change 

 of these conditions may influence the true 

 breeding of a strain, but without sufiicient 

 reason, since such an assumption is surely 

 unwarranted as long as the question has not 

 been actually tested in a scientific way. The 

 necessity, in certain cases, to observe certain 

 'gardener's tricks,' in order to get the best 

 results in raising particular races, strongly 

 favors the opinion that environment actually 

 has something to do with it, and scientific 

 experiments with this in view should be made 

 by all means. Where de Vries succeeded in 

 breeding true his ' mutations,' the environ- 

 ment of the botanical garden was not averse 

 to the experiment, and in this connection it 

 is suggestive that his chief success was at- 

 tained with (Enothera lamarchiana — an es- 



" For those who have no practical experience in 

 gardening, the study of a few items in Bailey, 

 ' The Cyclopedia of American Horticulture,' will 

 give an idea of the immense variety of these 

 tricks. 



caped garden-form, to which apparently the 

 botanical garden was congenial." 



Finally, in order to define my standpoint as 

 precisely as possible, and in order to obviate 

 unnecessary discussion of minor and irrelevant 

 points, I shall condense everything I have said 

 into five questions, and if anybody wants to 

 challenge my propositions, I ask him to do so 

 in terms as laid down here. 



1. Does the ' elementary species ' of de Vries 

 correspond to Darwin's conception of ' variety/ 

 and is my definition of ' species ' (' taxonomic 

 species') acceptahle? 



2. Are selection and segregation the essen- 

 tial features in pedigree-culture? 



3. Are de Vries's experiments, aside from 

 their greater accuracy and refinement, essen- 

 tially identical, in their method, with those 

 of the earlier breeders, as, for instance, re- 

 corded hy Darwin? 



4. 7s it advisable that breeding experiments 

 should be repeated with due regard to environ- 

 ment, before a final judgment is to be pro- 

 nounced, and are de Vries's experiments de- 

 fective on this point? 



If the answer to these four questions is 

 ' Yes,' then my contentions are recognized as 

 well supported, and the answer to the next 

 question should also be ' Yes ' — 



5. Should the validity of de Vries's muta- 

 tion theory be doubted, since he makes an 

 unwarranted distinction between two hinds of 

 variation, which further experiments possibly 

 will prove to be identical? 



If, however, anybody should be inclined to 

 answer 'no' to any or all of these questions, 

 I ask him to give reasons for so doing. I have 

 given my reasons for answering them in the 



" I call attention to Jordan's account of some 

 of Burbank's experiments (in Pop. Sci. Monthly, 

 January, 1905), where also the influence of the 

 environment in the production of variation ia 

 repeatedly emphasized, chiefly on pages 205 and 

 206. Possibly, if Burbank's attention is called 

 to it, he may be able at once to quote instances 

 where the true breeding of a certain strain de- 

 pends largely on the environment off'ered. This, 

 of course, should be the general rule, but it can 

 be clearly observed only in such cases where a 

 particular feature of the environment is known 

 to be responsible for a particular variation. 



