FISSION. 59 
was by the Belgian savant said to be homologous 
when it occurred between members of the 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. 
Where 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 L. 
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 
