SPECIES A^*"D srsspECiES. 235 



varieties of one species, forms which the less experienced authors 

 who preceded him had kept asunder. Now and then, no doubt, he 

 united very distinct species ; but, on the whole, we may with M. 

 Jordan regard the Linnean species as definite groups, and not passing 

 by gradual transitions one into the other. 



The progress of botanical science since it received its first 



great impulse from the labours of Linneus and Jussieu has been so 



rapid and continuous that it has, till quite lately, been impossible to 



stand still to review the question of species. In ail branches of 



natural history there has been a gradually increasing tendency to 



their multiplication from the greater precision which has of late 



years been introduced into the modes of observation. This is most 



the case in local Floras, which, as a rule, are the work of botanists 



who confine their attention to the areas regarding which they publish, 



or at the most extend their range only to neighbouring countries, 



which possess a similar Flora, ^here are, of course, exceptions, and 



it will almost always be found that the more general the range of a 



botanist's studies the more wide his opinion of the specific limit. 



That the increase in the number of species in each Floi'a has been 



continuous, and at the same time extremely gradual, will be evident 



to any one who examines and compares the local Floras of the present 



day with those of older date. Each generation of botanists avails itself 



of the observations of its predecessors as a foundation from which to 



advance further in the same direction. Believers in the permanence 



of species will require no proof that the forms of Euhus, or Rosa, or 



JRanuiiculus aqiiatilis, which are now recognised, were much the same 



a century ago as they are now, and the advocates of the mutability 



of species, knowing the great lapse of time required to produce 



even a small modification, will readily admit the fact. Little or no 



change has taken place since that time in the external circumstances 



under which these plants grow, and no modifying causes can be 



suggested which are likely to have produced a sudden tendency to 



variation in these genera. If the possibility of this in a single case 



be contended for, it will, we suppose, be certainly conceded that it 



cannot have happened in all the variable genera. And yet while 



there has been during the period mentioned a gradual increase in the 



number of forms regarded as of specific value, there is nothing like 



a common consent among botanists of the same period as to the 



particular forms which are to be considered as species or varieties. 



No two authors, nay no two editions, agree with one another. Again, 



B 2 



