182 SYSTEM. [SECTION 18. 



student down to the genus. Two such classifications were long in vogue : 

 First, that of Tournefort, founded mainly on the leaves of the flower, the 

 calyx and corolla : this was the prevalent system throughout the first half 

 of the eighteenth century; but it has long since gone by. It was suc- 

 ceeded by the well-known 



549. Artificial System of Linnaeus, which was founded on the sta- 

 mens and pistils. It consists of twenty-four classes, and of a variable 

 number of orders ; the classes founded mainly on the number and dispo- 

 sition of the stamens ; the orders partly upon the number of styles or stig- 

 mas, partly upon other considerations. Useful and popular as this system 

 was down to a time within the memory of still surviving botanists, it is 

 now completely obsolete. But the tradition of it survives in the names of 

 its classes, Monandria, Diandria, Triandria, etc., which are familiar in 

 terminology in the adjective terms monandrous, diandrous, triandrous, etc. 

 (2S4) ; also of the orders, Monogynia, Digynia, Trigyuia, etc., preserved in 

 the form of monogynous, digynous, trigynous, etc. (301) ; and in the name 

 Cryptogamia, that of the 24th class, which is continued for the lower series 

 in the natural classification. 



550. Natural System. A genuine system of botany consists of the 

 orders or families, duly arranged under their classes, and having the tribes, 

 the genera, and the species arranged in them according to their relation- 

 ships. This, when properly carried out, is the Natural System; because 

 it is intended to express, as well as possible, the various degrees of relation- 

 ship among plants, as presented in nature ; that is, to rank those species 

 and those genera, etc., next to each other in the classification which are 

 really most alike in all respects, or, in other words, which are constructed 

 most nearly on the same particular plan. 



551. There can be only one natural system of botany, if by this term 

 is meant the plan according to which the vegetable creation was called into 

 being, with all its grades and diversities among the species, as well of past 

 as \of the present time. But there may be many natural systems, if we 

 mean the attempts of men to interpret and express that plan, systems 

 which will vary with advancing knowledge, and with the judgment and 

 skill of different botanists. These must all be very imperfect, bear the 

 impress of individual minds, and be shaped by the current philosophy of 

 the age. But the endeavor always is to make the classification answer to 

 Nature, as far as any system can which has to be expressed in a definite 

 and serial arrangement. 



552. So, although the classes, orders, genera, etc., are natural, or as 

 natural as the systematist can make them, their grouping or order of 

 arrangement in a book, must necessarily be in great measure artificial. 

 Indeed, it is quite impossible to arrange the orders, or even the few classes, 

 in a single series, and yet have each group stand next to its nearest relatives 

 on both sides. 



553. Especially it should be understood that, although phanerogamous 



