PART I. 



MORPHOLOGY, 

 COMPARATIVE ANATOMY. 



CHAPTER I. 

 GENERAL MORPHOLOGY. 



General Remarks. The functions of plants being comparatively 

 simple, and, to speak in general terms, limited to those of nutrition 

 and reproduction, the physiological classes of organs are few. The 

 immense diversity which presents itself in the Vegetable Kingdom 

 depends chiefly upon varieties in the form of organs performing 

 similar functions. In addition to this, the organs of plants are 

 displayed externally, not enclosed in cavities or surrounded by an 

 integument or shell like that of animals, so that the external forms 

 of plants furnish a guide to the discrimination of their most 

 essential characters. 



Plants are destitute of the nervous system and the organs subservient to 

 it, and are without the connected system of blood-vessels, by which, in 

 the majority of animals, the unity and interdependence of the nutritive 

 processes are maintained. Plants consist simply of organs of absorption, 

 assimilation, respiration, and reproduction, all composed of comparatively 

 uniform elementary tissues, and supported by a solid framework or skele- 

 ton, which is more strikingly developed according to the number of organs 

 associated in one community, and more diverse in its mode of construction 

 according to the variety and complexity of the physiological kinds of organs. 



The organs of plants are not only of few physiological kinds, but 

 their variations in form depend on secondary modifications of a 

 very few fundamentally diverse elements. The object of Vegetable 

 Morphology is to ascertain what these elements are, and to trace 



