26 PROCEEDINGS OF THE 



part of the whole fabric of the Linnean philosophy. Let me 

 illustrate this statement by a brief reference to his theory of 

 reproduction. Eegarding the body of the plant as consisting of 

 a cortical and of a medullary substance, he held the latter to be 

 the principal seat of life and of the reproductive capacity in 

 particular. The medulla extends into the flower and there gives 

 rise to the ovary and the seed, and even to the embryo {cormlum) 

 in the seed (' Philosophia,' p. 87). Hence he concluded that the 

 development or reproduction of plants (generatio) is essentially a 

 continuation. This being so, it is not surprising to find him 

 drawing the logical inference, that the production of new species of 

 plants is negatived by this continuity in their reproduction (p. 99); 

 or, as he puts it elsewhere (p. 101), " that species are most constant 

 because their reproduction is a true continuation." 



It is difficult to imagine how anyone with this mental attitude 

 could be supposed to harbour an idea of the mutability of species. 

 It is, however, true that Linnaeus did admit the possibility of the 

 origin of new species, not indeed by variation, but by hybridisation. 

 In the dissertation ' De Peloria ' (Amoen. Acad, i.) it is suggested 

 that the peloric form of Linaria may be a new species and possibly 

 a hybrid ; and in the dissertation ' PlantaB Hybridse ' (Amcen. 

 Acad, iii.) the idea of the production of new species by hybridisation 

 is further developed. But this is merely a side-issue, that does 

 not directly bear upon the main question. More relevant is the 

 consideration of his views as to the relation between species and 

 varieties, set forth in the 'Philosophia Botanica.' " There are," he 

 says (p. 100), "as many varieties as there are diverse plants pro- 

 duced from the seed of the same species." A variety he defines as 

 " a plant changed by some accidental cause, such as climate, soil, 

 temperature, winds, &c., and may be restored (to its ])rimitive 

 form) by a change of soil." The distinguishing features of 

 varieties are their size, the doubling of their flowers, the crispation 

 of their leaves, their colour, taste, and smell. Further on (p. 225) 

 in the same work he dwells upon the great difficulty and labour 

 involved in the task of distinguishing between species and varieties. 

 Mistakes, he says, are often made on account of the exuberance 

 of nature, of differences of climate and habitat, and of the short 

 term of human life, but they may be avoided by the cultivation 

 of the doubtful plants in various soils and situations, by careful 

 study of the plant itself, especially of its fruit, as well as of allied 

 species, and by remembering that the laws of nature are constant 

 and never make a leap (mmqtimn saltus facientes). That this 

 expression of his ideas as to variation was not satisfactory, even to 

 himself, is apparent from the suggestion subsequently made in the 

 appendix to the dissertation on Hybrid Plants (Amoen. Acad, iii.) to 

 the effect that the varieties of plants do not only depend upon the 

 nature of the soil, nor are they changed by cultivation : " the double 

 Peony or Narcissus," he says, in illusti'ation, " is not changed 

 by the soil into the single form, nor is it on that account a dis- 

 tinct species." This important emendation certainly marks an 



