OF CLASSIFICATION. 269 



Mrs. B. Your observation is perfectly just ; and, in 

 fact, botanists can only, with any degree of certainty, com- 

 pare such organs as are adapted to the same class of func- 

 tions. For instance, you will readily admit that the brain 

 is of higher rank than any single nerve, and the heart su- 

 perior to any other blood-vessel : but if you inquired 

 whether the heart or the brain were of greatest impor- 

 tance, it would be quite out of my power to answer you. 

 If you will promise not to laugh at me, I will venture upon 

 a very trivial comparison. 



Caroline. Pray, let us hear it, Mrs. B. ; I am so fond 

 of comparisons indeed, I often understand them better 

 than arguments. 



Mrs. B. You are, no doubt, aware that a captain is 

 of higher rank in the army than a lieutenant, and a colo- 

 nel than a captain ; you know, also, that the governor of 

 a province is of more elevated dignity than the mayor of 

 a small town : but, pray, how would you answer, if I ask- 

 ed you whether a captain or a mayor ranked highest ? 

 You might say, in some particular cases, the one takes 

 precedence of the other ; but that would depend entirely 

 upon arbitrary decision, and not on the nature of their 

 functions, which will not admit of comparison. Now, 

 if you apply this simile to vegetable physiology in which 

 there are two great classes of functions ; one of which be- 

 longs to the re-production, and the other to the nutrition, 

 of plants ; you will understand that those organs alone ad- 

 mit of comparison which belong to the same class. 



Emily. Pray, give us some example of this ? 



Mrs. B. In re-production, for instance, the organ of 

 most importance is the embryo ; next to that the stamens 

 and the pistils, which, taken collectively, are no less in- 

 dispensable than the embryo, for without them it cannot 

 receive life. Then follow the integuments which protect 

 the embryo ; and next those which guard the pistils and 

 the stamens ; after these come the accessary organs, such 

 as the nectary. You see that I have already given five 

 different degrees of importance to the organs of re-pro- 

 duction. 



1451. How does Mrs. B. answer her! 1452. What comparison 

 does Mrs. B. make to illustrate the subject! 1453. How is this to 

 be applied to vegetable physiology! 1454. In re-production in what 

 order of importance are placed the organs,and how many of these organs 

 are thus named! 



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