1.'30 TAXONOMY. 



HI. (}n the diffiriut Points of' View under which an Organ y 

 or a System of Orgaji.f, may be considered. 



193. 



In order to seize these points of view, we must examine 

 as well the internal symmetry of an organ, as its relations to 

 other organs, or to the whole plant. Our attention, there- 

 fore, must be directed to the presence or absence of the or- 

 gan, — to its situation and relative position, — to its numerical 

 proportion, — to its size, — its external form, — its duration, — its 

 uses, — and to its sensible properties. 



194. 



In this examination, the most important matter is, that we 

 should be convinced of the presence or absence of an organ. 

 We must endeavour to avoid the errors which may arise 

 from abortion or union of parts. Especially we must put 

 more value on the positive characters, which express the pre- 

 sence of an organ, than on the negative, which indicate its 

 absence. 



195. 



The situation and relative po.sition of parts is their most im- 

 portant point of view. This situation may either be consider- 

 ed simply with reference to the place of insertion ; or with re- 

 ference to the dissimilar organs which are attached to the 

 same place ; or, lastly, with reference to tfie similar organs 

 which arise in different places. 



With respect to the first oi^ these ; the essential situation of 

 every organ is always so defined, that we understand its true 

 support ; that is to say, we understand what is the part by 

 which it is nourished, or from which it springs. To give an 

 instance, — the situation of the embryon must not be considered 

 in relation to the fruit, but to the umbilicus, or to the point 

 where the funiculus uml)ilicalis is inserted. In this sense 

 we observe that almost all embryons direct their radicle to- 

 wards the funiculus imibilicalis. AVhen we say, therefore, 



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