150 THE NATURALIST, 



DWAEFISM AND ATROPHY. 



By M. FEAN901S Crepin, 



Professor of Botany a " VEcole d' Horticulture" Gand. 



The florist, and above all, the monographist, with mind absorbed in 

 details, too often loses sight of certain general facts of great importance. 

 Amongst plants there exist two causes, the effects of which frequently 

 mask the veritable characters of species. I refer to Dwarfism (nanisme) 

 and Atrophy, which are opposed to " excessive development " fgeantisme,) 

 and Hypertrophy. In fact, under certain conditions, plants decrease 

 considerably in height, their vegetative organs shrini^, the stems and branches 

 lose their habitual dimensions, the inflorescence is modified in its details, 

 and certain floral organs are abortive or atrophied. These changes may 

 take place owing to a too dry and arid soil, to a situation too much ex- 

 posed to the sun, or too shady. On the other hand, on land too fertile, in 

 a fresh and shady place, or more particularly in the neighbourhood of the 

 sea, the same plant may be modified in a contrary direction. 



In default of taking into account these general causes of variation, botan- 

 ists are misled into describing as distinct species, forms simply affected by 

 atrophy or hypertrophy, — dwarfs or giants. Neglecting the attentive ex- 

 amination of habitats, they afiervvards discover in dried specimens, diver- 

 gences which they cannot explain, except by an innate difference in the 

 objects themselves : they take no account either of soil or humidity, dry- 

 ness, shade, &c., and thus take for a distinctive character what is but an 

 accident to an individual plant. * We might mention numerous species 

 created in this manner, with varieties dwarfed or developed more than 

 ordinarily. 



As I have already stated, an excess of development or impoverishment 

 frequently brings in its train quite a suite of differences, which would 

 almost make us believe it a separate and distinct species, if not on our 

 guard against modifying causes. This series of differences, which appears 

 to make a complete series of excellent specific characters, constitutes at the 

 bottom of it but one simple divergence repeated in all the similar organs, 

 and at once disappears from all these if the modifying causes are overcome 

 and removed. At first sight descriptions of these critical forms, wrongly 

 elevated to the rank of species, appears to include equally differential 



