ARTIFICIAL CLASSIFICATION. 85 



invariable; so that all those things which are changed by 

 propagation, are justly excluded from the principles of the 

 system. The Duration of plants, their Stature, their Taste 

 and Smell, even sometimes their Colours, and also their situa- 

 tion and time of flowering, are all things and relations which 

 we must consider variable; whilst, on the other hand, the 

 Forms and Numerical Proportions of the parts of fructifica- 

 tion, are seldom subject to change. These, therefore, must 

 constitute the principle of classification. 



128. 



We must especially employ, as the grounds of classifica- 

 tion, such organs, as, besides their constancy and invariable- 

 ness, are also found in the greatest number of plants ; and, 

 when it is possible, such parts too as are easily observed, and 

 which appear at the same time. 



But the two latter requisites are of less importance than 

 the first; and cannot always, according to the nature of 

 things, be obtained. There are a great many plants, whose 

 essential parts are so small, and lie so hidden, that they can 

 be discovered only by the aided eyes, and after previous, of- 

 ten troublesome, preparation. The finer differences in the 

 structure of the Mosses, Fungi, and other imperfect plants, 

 cannot be observed without powerful magnifying glasses. 

 The situation of the embryon and of its parts in the seed, 

 can only be exhibited by particular preparation. But as 

 these relations are among the most stedfast and important, 

 we must avoid no labour to become acquainted with them ; 

 and no system can be reproached for paying regard to those 

 parts and relations. 



The same remark applies to the want of cotemporaneous 

 growth. It is impossible to determine a plant with cer- 

 tainty, before its vegetation has come to maturity ; because 

 then only are all the essential parts unfolded, and a plant 

 which has been observed for years, without being seen to 

 bloom, or to carry fruit, cannot be defined with certainty, 

 and in a scientific manner. Especially the ripening of the 

 fruit is to be waited for ; because, as we shall see, important 



