C4 II. PERMANENCE OF SPECIES. 



the technical species ; thus showing them to be largely 

 conjectural, or arrangements by opinion and caprice. — 

 8. Hence arise the differences as to aggregate and segre- 

 gate species ; some botanists combining more, other bo- 

 tanists dividing and subdividing on slighter differential 

 characters. — 9. Since they are the conjectural or techni- 

 cal species which are described in books, and are enume- 

 rated by name in catalogues, the Phyto-geographer is 

 compelled to treat these as if they were the true natural 

 species. — 10. And where he finds Authors differing in 

 their grouj)ings of individuals into such technical species, 

 he is often obliged to adopt the aggregate, in preference 

 before the segregate species, on account of the greater 

 difficulty and uncertainty in tracing the distribution of 

 segregates by aid of books and catalogu.es. * 



* " It is very muoli to be wished," write Drs. Hooker and Thomson, 

 " that the local botanist should commence his studies upon a diametrically 

 opijosite principle to that upon which he now proceeds, and that he should 

 endeavour, by selecting good suites of specimens, produced under all varia- 

 tions of circumstances, to determine how few, not how many species are 

 comprised in the flora of his district." .... " The unavoidable tendency 

 of the human mind, when occupied with the pursuit of minute differences, 

 is to seize on them with avidity, and to relinquish them with regret ; hence 

 the iiTesistible desire to rest contented with a character, however bad, so 

 long as it is obtained with difficulty, and in the observer's opinion is tole- 

 rably constant. It is strange that local naturalists cannot see that the dis- 

 covery of a form uniting two others they had previously thought distinct, 

 is much more important than that of a totally new species, inasmuch as 

 the correction of an error is a greater boon to science than is a step in ad- 

 vance." (Flora Indica, vol. i. pages 35, 36). 



