■iiii': CKNUS KdSA 245 



dishenrteninsf, but to the enquirinfj mind readily understand- 

 able. In the first place, so casually are rose specimens 

 accumulated, and so effectually does the process of drying 

 repress any but the most unrehable of characters, that forms', 

 in reality most diverse, in the end look precisely alike ; for 

 example, it is quite an easy matter to produce a form o( J?osa 

 coriifolia so similar as a herbarium specimen to a member of 

 the tomentosa group that even to the trained eye they are 

 almost indistinguishable. If then the original descriptions of 

 species be based on such material, as they often enough were, 

 how little can we expect such accounts to square with the 

 roses as they grow in nature, and how futile, therefore, our 

 endeavours to determine a plant by their aid. Even with an 

 ordinary genus a dried specimen may prove troublesome 

 enough although the obstacles to a correct determination are 

 not insurmountable, and so would it be with Rosa were it not 

 that its members — call them species, little species, elementary 

 species, microgenes or what you will — are so excessively 

 variable that another difficulty arises. In some cases no two 

 bushes are exactly alike; by that very fact they practically 

 invite the attention of some individual blessed (?) with the 

 "mihi" — or what Crepin used to call the "bush-mania" — - 

 who forthwith sees material for a possible new species. 

 Obviously enough, the most hardened sinner would avoid the 

 error of describing, as distinct, plants differing merely in some 

 microscopic denticle on the back of the main leaf-serrations or 

 in characters of similar value. Far from it, he' selects his 

 specimens from a bush as remote from the nearest book 

 description as possible and upon those erects his "new" 

 species. Now in all of its many inconstant characters, the 

 variation in Rosa follows the ordinary frequency distribution 

 of a Quetelet curve, as a very simple test will demonstrate. 

 Collect, for example, a quantity of terminal leaflets from 

 various bushes of the R. lutetiana group ; measure their 

 lengths, ignoring absolutely the fact that they are plucked 

 from shrubs with large*, medium, or small leaves, and plot a 



* These are the actual words used in certain dichotomous tables to separate 

 alleged species ! 



