8 MORPHOLOGY, OR COMPAEATIYE ANATOMY. 



out the laws under which they acquire the different forms which 

 they present in fully developed plants. 



The methods of Morphology consist in the comparative study of the 

 forms of organs throughout extensive series of plants, the study of mal- 

 formations arising from arrested, excessive, or perverted growth (terato- 

 logy), and the study of the progressive development of plants from their 

 embryonic forms (organogeny). 



Simplest Plants. The simplest plants (fig. 1) consist of solitary 

 cells or bladders of membrane containing a viscid fluid called 

 protoplasm, in which latter the vitality of the plant is concentrated. 

 By the aggregation of such cells into threads, tubes, plates, spheres, 



Simple cellular plants. 



A. Yeast-plant vegetating. C. Penicillium glaucum. 



B. AspergUlus glaucus. D. Mucor Mucedo. 



Magnified 200 diameters. 



and other forms (fig. 1, A, B, C, D), a gradually increasing com- 

 plexity is brought about. 



Higher Plants. What are called the higher classes of plants, 

 those most familar to uninstructed persons, are constructed of pre- 

 cisely the same elements, but exhibit the greatest morphological 

 complexity. The highest class of plants have conspicuous flowers. 



