310 TERATOLOGY. SUPPRESSION OF ORGANS. 



of the petals or sepals becomes more developed than the others. In Di- 

 cotyledonous plants, it is common to meet with pentagonal (figs. 535, 

 536, 537) and tetragonal (figs. 533, 534), symmetry, the parts being 

 arranged in fives and fours, or in multiples of these numbers. It is 

 common to find the stamens 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 verticils. No doubt the verticils 

 are often traced with difficulty, more especially when adhesions take 

 place. In Monocotyledons (fig. 538), the parts are usually in sets of 

 three, or in some multiple of that number, exhibiting trigonal symme- 

 try. 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 Acotyle- 

 dons are also arranged in fours. 



646. Teratology. There has thus been traced a tendency to sym- 

 metrical arrangement in plants. 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 organiza- 

 tion, 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 inter- 

 fere with the symmetry of the flower. Alteration in the symmetrical 

 arrangement, as well as in the forms of the different parts of plants, 

 have been traced to suppression or the non-development of organs, degen- 

 eration or imperfect formation, adhesion or union of one part to another, 

 multiplication of parts, and unlining or chorization. The study of 

 Teratology (r^og, a monstrosity, and Xoyo?, treatise), or of the mon- 

 strosities occurring in plants, has led to many important conclusions 

 relative to the development of organs, and it is only by tracing the 

 parts of plants through all their stages and transformations, that correct 

 ideas can be formed as to their relations and forms. 



647. By suppression is meant the non-appearance of an organ at the 

 place where it ought to appear if the structure was normal; the organ 

 being wanting to complete the symmetry. This suppression is liable 

 to occur in all the parts of plants, and gives rise to various abnor- 

 malities. Suppression may consist in the non-appearance of one or more 

 parts of certain verticils, or of one or more entire verticils. In the 

 flowers of Staphylea (fig. 539), there are five parts of the calyx, five 

 petals, five stamens, and only two carpels; in many Caryophyllacete, 

 as Polycarpon and Holosteum (fig. 540), while the calyx and corolla 

 are pentamerous, there are only three or four stamens and three car- 

 pels; in Irnpatiens noli-me-tangere (fig. 541), the calyx is composed of 

 three parts, while the other verticils have five; in Labiate flowers, there 



