588 TAXONOMY. 



322. 



I. IDEA OP SPECIES. 



A species is that group of natural bodies which agree together in all 

 their essential, unchangeable characters. The idea of species com- 

 prises in it a congruency, that is to say, not a mere conformity, but 

 also a resemblance of its individuals. 



A species is the lowest of all the systematic groups, and consequently 

 the most fixed and conformable; no further differences are observable 

 amongst its individuals, all have consisted from the commencement of 

 this form, and continue so by the propagation of new and congruent 

 individuals. Yet differences in less essential characters may occur, for 

 example, in colour, and even in size, and such forms have been called 

 varieties. They originate from accidental circumstances, which cannot 

 be predicted. Others, which have been called sub-species, exhibit a 

 greater conformity together, but which differ in some characters from 

 the type of the species, and these differences are continued through all 

 subsequent generations, which is not the case in mere varieties. But 

 they yet announce themselves as true individuals of the species by a 

 conformity in essential unchangeable characters, and therefore cannot, 

 notwithstanding these differences, be separated from it. 



323. 



One important character which especially identifies the sub-species 

 with the species is, that they are fertile together. This is a very 

 definite character, and which is subjected to no divarication; for how- 

 soever much the several sub-species of Coccinella variabilis, 111., differ 

 from each other, so much so that Fabricius considered them as forming 

 several species (viz. C. 10-punctata, C. 13-punclala, C. 10-pustulata, 

 &c.), we however find them in reciprocal connexion, and there is con- 

 sequently no doubt that they are all one species. Truly distinct species 

 never regularly *, or at least but rarely, intermix in a state of nature, 

 and certainly not fruitfully, although bastards (species hybridce), that 

 is, new intermediate ones originating from the intercourse of two species, 

 produced in a state of captivity, or in a state of life differing from their 

 original natural state, is not rare among the superior animals. In 

 reference to this, we may therefore say that sub-species and varieties 



* SPC above, '2.0'J. 



