216 HABIT AND INTELLIGENCE. [chap. 



above- ancestor of the species, and species to the character of 



of^rever-^ the ancestor of the genus, is, I beUeve, only a case of a 



sion. principle which is true far beyond the limits of species and 



genera. I believe that reversion sometimes occurs to the 



characters of very remote ancestors indeed, from which the 



species in which the reversion occurs is separated, not only 



by many myriads of generations, but by very profound 



changes. 



Circular One instance of this is among flowers. It can scarcely 



ral flowers' ^® questioned that the normal form of flowers is circular, 



and that (supposing the development theory to be true) 



flowers of bilateraP forms have been derived from circular 



ones by descent, with modification. It is to be observed, 



that flowers cannot be divided into two classes according 



as they are circular or bilateral : all the rose tribe have 



circular flowers, and all the foxglove tribe have bilateral 



ones ; but among the geraniums this character is variable 



within the genus — indeed, I believe, within the species. 



Individual flowers are sometimes found which are circular, 



though belonging to bilateral species. This variation is 



Peloria. common enough to have received a name, " peloria," and, 



on my view, it is a case of reversion. 



Another instance of what I believe to be reversion is far 



Non- more extraordinary. Non-sexual generation is usually a 



geni'ration proof, Or at least a concomitant, of comparatively low 



organization : it is universal among the lowest animal 



forms ; it does not occur among the true mollusca, at least 



in any ordinary form \J but it is common among the marine 



iu womis, worms, which are about on a par with the Gasteropodous 



mollusca in grade, of organization, though very unlike them 



in ])lan. I shall also show reason for believing that aU the 



1 Bilateral may sound pedantic, but I prefer it to irregular, which is an 

 inaccurate expression. 



- The only known instance of non-sexual generation among the moUusca 

 is a very extraordinarj'' one, which occure in their highest class, the 

 Cephalopoda. The male of the cuttle-fish tribe bears no resemblance to 

 the female ; it is produced by one of the arms of the female being detached 

 and undergoing a peculiar development, which transforms it into a male 

 animal, or at least a male organ. 



