b ARRANGEMENT OF ORGANS. 



established, though in matters of detail much remains 

 to be cleared up, even in such important points as the 

 share which the axis takes in the construction of the 

 flower and fi'uit, the nature of the placenta, the con- 

 struction of the ovules, and other points. 



The facts already known justify the adoption of a 

 standard or typical arrangement as just mentioned. 

 The intrinsic value of this- type is shown by the facility 

 with which all varieties of form or arrangement may 

 be explained by reference to certain modifications of it. 

 It must, however, be considered as an abstraction, and 

 should be looked on in the light rather of a scaffolding, 

 which enables us to see the building and its several 

 parts, than of the edifice itself, but which latter, from 

 oiir imperfect knowledge and limited powers, we could 

 not see without some such assistance. 



The typical form may be, hypothetically at least, con- 

 sidered as the primitive one transmitted by hereditary 

 descent from generation to generation, and modified to 

 suit the requirements of the individual, or in accord- 

 ance with circumstances. If it be borne in mind that 

 it is but an artificial contrivance, more or less true 

 a means to an end, and not the end itself no harm 

 will arise from its employment ; and as knowledge 

 increases, or as circumstances demand, the hypo- 

 thetical type can be replaced by another more in 

 accordance with the actual state of science. 



Teratological changes in the arrangement of organs 

 depend upon arrest of growth, as when parts usually 

 spirally arranged remain verticillate, owing to the 

 non-development of the internodes, or to excessive 

 gi'owth, or development ; but in many instances it is 



