FISSION. 59 



was by the Belgian savant said to be homologous 

 when it occurred between members of thd same whorl, 

 e. g. between the sepals of an ordinary monosepalous 

 calyx, or heterologous when the separation took place 

 between members of different whorls, as when the 

 calyx is detached from the ovary, &c. The former 

 case would thus be the converse of cohesion, the latter 

 of adhesion. 



To the adoption of these words there is this great 

 objection, that we can but rarely, in the present state 

 of our knowledge, tell in which group any particular 

 illustration should be placed. 



The terms adopted in the present work are, for the 

 most part, not necessarily intended to convey any idea 

 as to the organogenetic history of the parts affected. 

 \Vhere a single organ, that is usually entire, becomes 

 divided the term Fission is used ; in cases where parts 

 of the same whorl become isolated, the word Dialysis 

 is employed, and in the same sense in which it is 

 generally used by descriptive botanists, and where the 

 various whorls become detached one from the other, 

 the occurrence is distinguished by the application of 

 the term Solution. 



CHAPTER I. 



FISSION. 



When an organ becomes divided it receives at the 

 hands of descriptive botanists the appellations cleft, 

 partite, or sect, according to the depth of the division ; 

 hence in considering the teratological instances of this 

 nature, the term fission has suggested itself as an appro- 

 priate one to be applied to the subdivision of an habi- 

 tually entire or undivided organ. It thus corresponds 

 pretty nearly in its application with the term Chorisis 



