PART II. 



SPECIAL ANATOMY AND PHYSIOLOGY OF PLANTS, 

 AND OUTLINES OF THEIR CLASSIFICATION. 



CHAPTER XIII. 

 CLASSIFICATION. 



264. In order to obtain a definite knowledge of the com- 

 parative structure of plants, it is necessary here to take up 

 in order the different groups, and to study with some care 

 the more important modifications and differences noticeable 

 in the plant-body. This study, so taken up, is intimately 

 connected with the classification of plants ; the differences 

 and modifications of structure which we study in order to 

 gain a better knowledge of plants as a whole, are the very 

 ones which serve to separate the vegetable kingdom into 

 larger or smaller groups. This part (Part II.) of this trea- 

 tise will, therefore, include the outlines of the Classification 

 of Plants, as well as a discussion of Special Morphology. 



265. (1.) In the classification of living objects they "are 

 arranged according to the totality of their morphological re- 

 semblances, and the features which are taken as the marks 

 of groups are those which have been ascertained by observa- 

 tion to be the indications of many likenesses or unlikenesses."* 

 Such an arrangement is " a statement of the marks of sim- 

 ilarity of organization, and of the kinds of structure which, 

 as a matter of experience, are universally found associated 

 together." 



* T. H. Huxley in the article "Biology," in "Encyclopaedia Britan- 

 nica," ninth edition, Vol. III., p. 683. 



