1.] CHAPTER I. GENERAL MORPHOLOGY. 5 



is determined by the protoplasm ; for the cell-walls, of which, in 

 many cases, the body largely consists, and which give to it its form, 

 are developed from and by the protoplasm. Hence the study of 

 the morphology of plants is the study of the processes and results 

 of the formative activity of their protoplasm ; and these are to be 

 traced both in the variety of form presented by different plants, 

 and in the various stages in the development of anyone individual 

 plant. 



CHAPTER I. 

 GENERAL MORPHOLOGY. 



1. The Segmentation of the Body. The body of a plant 

 may be either segmented into members, or unsegmented. The 

 members of a segmented body may either be all similar, or they 

 may be similar and dissimilar. Segmentation into similar 

 members is termed branching. 



When the body is unsegmented, or segmented only into similar 

 members (i.e. branched), it is termed a thallus. A plant of this 

 constitution is termed a Thallophyte. 



The primary segmentation of the body into dissimilar members 

 consists in the differentiation of shoot and root. A plant of this 

 constitution is termed a Cormophyte. 



The Root is usually segmented, but only into similar members : 

 it occasionally gives rise to (adventitious) shoots. 



The Shoot may be either unsegmented, or segmented into 

 similar or dissimilar members. A shoot which is either unseg- 

 mented, or segmented only into similar members, is termed a 

 thalloid shoot. A shoot which is segmented into dissimilar 

 members presents an axial member, the stem, bearing dissimilar 

 lateral members, the leaves ; stem and leaf may be further seg- 

 mented into similar members, that is, be branched ; such a shoot 

 is termed a leafy shoot. 



Though the ideas of shoot and root are correlative, the one involving the 

 other, yet there are cases in which the body consists of shoot only, the root 

 being suppressed ; as in the gametophyte of Mosses ; in the sporophyte of Salviuia 

 and Psilotum among Vascular Cryptogams ; and in Utricularia, Epipogou, and 

 Corallorhiza among Phanerogams. In many plants no root is developed until 

 after the stem and leaves have begun to appear. The shoot, in these cases, is 

 recognized as such, and is distinguished from a thallus, by being differentiated 

 into stem and leaves. 



