Swallowtail butterfly tiger swallowtail), Y-linkage determines whether the females are either wild-type (yellow and black) or melanic (dark melanin replaces the yellow background). This genetic difference stems from the fact that melanism is controlled by a single gene, which controls the level of dopamine in the organism. The enzyme BAS, which assists dopamine in producing the yellow pigmentation, normally found on the wings' background, is suppressed. Without the pigmentation, the butterfly appears mostly black (the melanic form) and is a Batesian mimic of "Battus philenor", the pipevine swallowtail. There are also "Papilio glaucus" that are not wholly black; several possess an intermediate
Comma character 44 (0x2C) corresponds to the comma symbol. The HTML numeric character reference is codice_1. In many computer languages commas are used as a field delimiter to separate arguments to a function, to separate elements in a list, and to perform data designation on multiple variables at once. In the C programming language the comma symbol is an operator which evaluates its first argument (which may have side-effects) and then returns the value of its evaluated second argument. This is useful in "for" statements and macros. In Smalltalk, the comma operator is used to concatenate collections, including strings. In Prolog,