90 



MORPHOLOGY, OR COMPARATIVE ANATOMY. 



arrangement is still more evident, especially where there exist great num- 

 bers of a particular kind of organ, as in the mixed petals and stamens of 

 Nymph&a, and the multiple pistils of Ranunculus, Magnolia, &c. 3n Caly- 

 canthus all the organs follow on in a continuous spiral. 



In other cases the floral organs are developed simultaneously, when a 

 true whorl is produced. 



Fig. 158. 



Fig. 159. 



Fig. 158. Calyx of the Rose ; the numbers indicate the sequence of the sepals from without 



inwards, or from below upwards. 

 Fig. 159. Section of the calyx of the Rose; the numbers as in the preceding figure. 



Number of Parts. According to the number of parts in a cycle 

 or apparent whorl, these are distinguished as dimerous or binary, 



Fig. 161. 



Fig. 160. Diagram of the $ spiral arrangement of the parts of the flower with bract and 



lateral bracteoles; O * ne situation of the axis. 

 Fig. 161. Diagram or ground-plan of the 3-merous flower of the Tulip. 



