38 MORPHOLOGY, OK COMPARATIVE ANATOMY. 



Fig. 38. 



Fig. 35. Fig. 36. Fig. 37. 



Fig. 35. Btem of Opuntia. Fig. 36. Stem of Melocaetus. 



Fig. 37. Cylindrical and ribbed stem of Cereus. 



Fig. 38. Diagram to illustrate the nature of a sympode, the imperfect separation (so called 

 adhesion) of leaves, and the uplifting of the latter with the growth of the shoot; 

 the primary shoot ending in a terminal bud which is deflected to one side, la, 

 one of the leaves of the primary shoot 1, in its ordinary position. 1 b, another leaf 

 of the same shoot adherent to or undetached from 2, the shoot produced in the 

 axil of 1 b, and carried up with 2 in its upward growth. The shoot 2, 2, with its 

 leaves 2 a, 26, grows in the same manner and others succeed it. Ihe portion of 

 the main axis marked 1,2, 3, 4, 5 in one vertical line is a sympode. being composed 

 not of one continuous axis of one and the same generation, but of a series of axes 

 of different and successive generations, ranged in vertical order. 



Ramification. The same general methods occur in the branching of 

 roots, of stems, of leaves, and of inflorescences, and indeed are also met 

 with in purely cellular plants, as in Algae and Fungi. Caulerpa, though 

 strictly unicellular, has mimic stem-hranches, leaves, and roots. Growth 

 takes place by means of growing points (puncta veyetationis), which will he 

 more fully described under the head of Minute Anatomy, and which, in 

 the case of stems, are enclosed within, and form the central terminal mass 

 of the buds. The growing point is terminal or lateral, primary or secondary. 

 If at the end of a shoot or branch it is terminal and* primary, or of the 

 Jirst degree; if at the side of a shoot it is lateral and secondary, or of the 

 second degree. In the latter case it is lateral because it is pushed out from 

 the side of the primary shoot beneath its apex, and it is secondary because 

 it is necessarily formed after the primary growing-point, and belongs to 

 a subsequent generation. In like mariner we may have in succession ter- 

 tiary buds, or shoots of the third, fourth, fifth degree, and so on. 

 Monopodial branching. By the growth of terminal buds or growing- 



