362 THE POPULAR SCIENCE MONTHLY. 



Linnaeus, besides, saw the necessity of bringing together all the 

 descriptions of plants already existing, and of wording them in 

 such a way that, without losing anything essential in the descrip- 

 tion, they should occupy the smallest possible space. Such a con- 

 densed description is now known as a diagnosis. 



When he had accumulated a considerable number of diagnoses 

 he saw that it was difficult to find one's way through them, and 

 he set about arranging them after some of the most striking 

 characteristics which did not necessarily indicate relationship, 

 but were simply as a means of classification and recognition. He 

 took for this first the number of stamens, bringing all plants with 

 one stamen in the flower together, all with two, three, four, five, 

 ten, etc., into their several classes, in this way creating the groups 

 of the Monandra, Decandra, Polyandra, etc. 



Having done this, he recognized that a subdivision of these 

 groups was desirable ; that many plants with the same number of 

 stamens yet differed considerably among one another ; and these 

 smaller groups he called genus, plural genera. Such a genus now, 

 for example, is the buttercup, which he called Ranunculus. He 

 saw that further subdivision could take place, and that there were 

 a great many plants which, though evidently all buttercups, yet 

 differed sufficiently to be distinct. So he resolved to give every 

 plant two names, the first one being the genus name, here Ranun- 

 culus, the second one expressing some property of that particular 

 kind of Ranunculus, and thus indicating the species. Thus he 

 found, for example, that one buttercup had an acrid taste, and he 

 called it the acrid buttercup in Latin, Ranuncidus acris ; that 

 another one always grew on marshy places ; he called it the marsh 

 buttercup in Latin, Ranunculus palustris, etc. 



Latin names were used simply as a matter of convenience, as 

 it was much easier to know one Latin name than a dozen names 

 in a dozen different languages for the same plant. Linngeus's 

 system was consequently one of mere convenience and thoroughly 

 artificial. 



It had, however, already been recognized that certain plants 

 belong naturally together, as grasses, for example, while Lin- 

 nseus's system often placed two grasses very far apart. This 

 conception of relationship, however, could not be expressed well 

 before Darwin had shown that plants had not always been as 

 they are now, but that the higher plants had gradually been 

 developed from the lower ones. Then an entirely different sys- 

 tem arose a system which expressed the relation of plants in 

 the way of a genealogical tree ; this system is generally known 

 under the name of the natural system. It is after this natural 

 system, which expresses our conception of the blood relation be- 

 tween the different plants, that our present herbaria are arranged, 



