TERATOLOGY — SUPPRESSION OF ORGANS. 365 



bers. The stamens are often more numerous than the petals, and in 

 that case they are arranged in different verticils, each alternating with 

 that next it. Thus, if there are five sepals, five petals, and twenty 

 stamens, the latter are considered as forming four verticUs. No doubt 

 the verticils are often traced with difSculty, more especially when 







Vr 



Fig. 636. "Pig. 636. Fig. 637. 



cohesions or adhesions take place. In Monocotyledons (fig. 637) the 

 parts are usually in sets of three, or in some multiple of that number, 

 exhibiting trigonal symmetry. In Acotyledons, when any definite 

 number can be traced, it is found to be two, or some multiple of two. 

 The teeth of Mosses are in sets of four, or some multiple of four. 

 The spores of many Acotyledons are also arranged in fours (fig. 482, 

 p. 273). 



Teratology. — There has thus been traced a tendency to symmetri- 

 cal arrangement. But the parts of plants are often modified by natural 

 causes which cannot be explained. It is assumed that each of the 

 similar members of a flower have the same organisation, and a similar 

 power of development ; and hence, if among these similar parts some 

 are less, developed than others, they are considered as abortive, and these 

 abnormal states are traced to changes which take place in the earlier 

 .stages of growth. Such changes often interfere with the symmetry of 

 the flower. Alteration in the symmetrical arrangement, as well as in 

 the forms of the difierent parts of plants, have been traced to suppression 

 or the non-development of organs, degeneration or imperfect formation, 

 mhesion or union of parts of the same whorl, adhesion or union of the 

 parts of dififerent whorls, multiplication of parts, and deduplication 

 (sometimes called chorisis). The study of Teratology (rs^ag, a mon- 

 .strosity, and Xoyog, treatise), or of the monstrosities occurring in plants, 



Fig. 634. Diagram of tlie pentamerous Isostemonous flower of Crassula rubens. ccccc. 

 Parts of the calyx, pp P!PP, Petals alternating with the leaves of the calyx, ee eee, 

 Stamens alternating with the petals, a, Accessory hodies in the foim of scales, or a disk 

 .alternating with the stamens. These scales are often an abortive row of stamens, o, 

 ■Carpels alternating with the stamens, and opposite to the scales. Fig. 636. Diagi-am of 

 the pentamerous flower of Sedum Telephium. The stamens are ten, arranged in two alter- 

 nating verticils. The flower is Diplostemonous. Fig. 636. Diagram of the pentamerous 

 Diplostemonous flower of Coriaria myrtifolia ; the parts of the four whorls alternating, the 

 verticil of stamens being double. Fig. 637. Diagram of the trimerous Diplostemonous 

 flower of Omithogalum pyrenaicum. Stamens six, in two alternating verticUs. 



