AD FLOBAM INDICAM — SAXIFBAGE^. 59 



ficiency of specimens in different stages of development, and from 

 different conditions of soil, climate, &c., tlie oversight of minute 

 but permanent and natural characters, and the over-estimate of more 

 conspicuous but less constant unimportant ones, are, after all, 

 though the common, not the only, or in all cases the most numerous 

 causes of diversity of opinion as to specific limits in such a genus. 

 The subtler sources of error are, preconceived notions originating 

 with the circumstances under which the specimens are first brought 

 before us, alive or dried, and dominant ideas founded upon a pre- 

 vious study of the genus in other parts of the world. In short, all 

 the advantages which a skilled naturalist derives from familiarity 

 with his subject under other phases — ^from a full knowledge of the 

 labours of others, and from having himself studied the majority of 

 his materials in their native localities — have concealed within them 

 certain sources of errors in judgement which influence the results 

 of the closest observer and most skilful reasoner. 



Such being the case, we feel that something is required of us 

 beyond the simple assurance that we have given a more than 

 average amount of careful comparative and microscopic study to 

 so di£B.cult a genus ; we have, in the next place, well compared 

 our forms with the identical, analogous, and representative species 

 of Siberia, Europe, and North America; and we have collected 

 almost all our Scotch Saxifrages, and studied those of the Alps a 

 little in their native localities. "We have carefully examined 

 numerous specimens from almost all Indian collectors, and 35 

 out of the 39 species have been gathered by one or both of 

 us, many of them in numerous localities. Having upon these 

 data formed an approximate estimate of the limits of the Hima- 

 layan forms, and found that they allowed much latitude for differ- 

 ence of opinion as to a very considerable proportion of the species, 

 we sought some European standard work with the views of which 

 our Indian results might on the whole accord ; and have selected 

 Koch's * Flora Germanica,' as being that which best represents 

 our ideas of the limits of the European forms. Whether all these 

 forms of European or Indian Saxifrages are to be considered 

 specific, is quite another question, and one which we cannot solve ; 

 all we can do with propriety is to indicate what seem most marked, 

 and what least so. 



To put this matter in a practical form, we may say, that if we 

 carried out what appears to us the most extreme views that could 

 possibly be adopted towards uniting forms, we should reduce the 

 Indian Saxifrages to 26, by imiting as varieties, the three of the 



