24 GREENE 



In the progress of these enquiries into the mind of Linnaeus as to 

 the origins of species nothing that I have come upon has more deeply 

 interested me than his remark upon the two species of sundew com- 

 mon in northern Europe, Drosera roiimdifolia and D. longifolia. 

 They are very pecuHar plants, uncommonly interesting from several 

 points of view, and have in recent years profoundly engaged organ- 

 ographers and physiologists; but Linnaeus was most interested in their 

 ecology as bearing upon the problem of their genealogy. Both are 

 bog plants, though far enough from being found in every northern 

 bog. They seem to be particular about the kind of soil, the amount 

 of moisture, the nature of the exposure, and also the plant associates 

 amid which they will establish their habitation; and both species 

 are at perfect agreement as to all special details of bog environment 

 which they demand; for where one is found, there too is the other. 

 They are much alike in size, mode of growth, degree of hairiness, 

 form and color of flowers, etc., but the leaf blades in one are round, 

 while in the other they are so much elongated as to be called narrowly 

 oblong; and this one strong distinguishing mark is constant. There 

 are no plants among them to show leaves intermediate between orbic- 

 ular and oblong. They ought to be, and I think that by all botanists 

 except Linnaeus, both before his day and ever since, they have been 

 held distinct; and even he did not positively affirm the contrary, but 

 only expressed a doubt; and the sole reason he has for doubting the 

 validity of D. longifolia is, that it and its mate species always occur 

 under precisely the same conditions and together.^" It is such a 

 reason as none but a confirmed evolutionist could give; the expression, 

 perhaps unguarded, of a mind no longer very patient of the opinion 

 that two species of the same genus can have the same native environ- 

 ment. A creative fiat could, of course, as readily make two species 

 of a genus suited to certain conditions as one, and as easily twenty 

 as two; and so no believer in the special creation of all species could 

 have felt this doubt about the sundews to which Linnaeus gave expres- 

 sion. 



It has been thought that the mind of Linnaeus as to the absolute 

 fixity of species underwent a change between the years 1751 and 1762, 

 though only in so far as to induce him to admit the origin of more 



'"Habitat ubique cum praecedente; an itaque satis diversa species? Species 

 Plantarum, i Ed., p. 282; 2 Ed., p. 403. 



