The male duct vd becomes fleshy and muscular near its termination at the genital pore, forming the penis p. Attached to it is a diverticulum fl, in which the spermatozoa which have descended from the ovo-testis are stored and modelled into sperm ropes or spermatophores.
The spermatozoa differ from those of other animals in having the form of cells which sometimes perform amoeboid movements.
Though possessing a complete copulatory apparatus and producing large quantities of spermatozoa, they have lost their sexual instinct and play no part in the economy of the species.
Spermatozoa and ova.
The spermatozoa exhibit many differences in shape, size and proportions, in the various groups of birds.