GENERAL MORPHOLOGY. 135 



applications : as, for instance, aciculatus, as if torn by a needle ; 

 rimosus, with fissures or chinks ; sulcatus, punctatus, scrobiculatus, 

 granulosus, verrucosus, &c. ; and to these we may add the designa- 

 tions in use for a hairy surface, as, for instance, arachnoideus, lanu- 

 ginosus, tomentosus, pubescens, pilosus, setosus, strigosus, &c. Scien- 

 tific exactness can only be attained here by a more accurate 

 description of the parts in question, and especially by the charac- 

 terisation of their morphological or anatomical signification. 



74. In all plants, with the exception of the few which consist 

 only of one cell, the form depends upon the manner in which the 

 cells are combined together. The development of forms is here 

 dependent on two essential points, namely, the arrangement of the 

 newly formed cells, and the different expansion of those already 

 existing. These two determining causes are normally definite for 

 every individual species of plant and for each separate organ, but 

 are entirely incidental for plants in general. The expansion of a 

 plant, or the part of a plant, in one, two, or three dimensions of 

 space, may depend as well upon the arrangement of the developing 

 cells as upon the expansion of those already developed, or as upon 

 the two causes combined. 



This subject has hitherto been wholly neglected, although it must form 

 the foundation of the whole science of morphology, since on this alone 

 depends the development of forms in plants. The whole question will be 

 understood in all its relations if we only remember that when four new 

 cells arise in one cell (fig. 118.), they may be within the parent-cell, either 



118 c. 



oooo 



in a row, linearly ( C), or two and two beside each other (B\ forming a 

 plane, or, finally, may lie within the parent-cell, like the corners of the te- 

 traedron (^4), forming a solid body. Owing to the great difficulty, in most 

 cases, of observing the first origin of cells, a long time must elapse before 

 we shall be able to account for the origin of different forms. All future in- 

 vestigations into the history of development must, however, necessarily be 

 directed to this essential point, and it is here, therefore, that we have to 

 expect the most interesting laws for the science of morphology. We are 

 unable, at present, to express any general statements, and it must, there- 

 fore, suffice here to have drawn attention to the paramount importance of 

 this point. A few more special amplifications will be met with in a sub- 

 sequent part of our work, especially with reference to the stem and 

 the foliar organs. As the foundation of every plant is in all cases one 

 individual cell (spore or embryonary vesicle), within or out of which the 

 new cells which gradually form the whole plant are developed, in each 

 primary cell must lie the conditions according to which the subsequently 

 developed cells are arranged : since, however, the expansion of the indi- 

 vidual cell in the three dimensions of space depends essentially upon 



K 4 



