In the young of the common earwig the number of joints[139] in the antennae increases with age. Camerano, _l.c._, says that before emergence from the egg there are apparently only 8 joints in the antennae, and Fischer states that the larvae of _F. auricularia_ have at first only 8 antennal joints; later on 12 joints are commonly found, and, according to Bateson,[140] this number occasionally persists even in the adult individual. Meinert says[141] that the newly hatched _Forficula_ has either 6 or 8 joints, and he adds that in the later portion of the preparatory stage the number is 12. Considerable discrepancy prevails in books as to the normal number of joints in the antennae of the adult _F. auricularia_, the statements varying from 13 to 15. The latter number may be set aside as erroneous, although it is, curiously {213}enough, the one given in the standard works of Fischer, Brunner, and Finot. Meinert gives without hesitation 14 as the number; Bateson, _l.c._, found that 14 joints occurred in 70 or 80 per cent of adult individuals, that 13 was not uncommon, that 12 or 11 occasionally occurred, and that the number may differ in the two antennae of the same individual. These variations, which seem at first sight very remarkable, may with probability be considered as due to the fact that in the young state the number of joints increases with age, and that the organs are so fragile that one or more of the joints is very frequently then lost, the loss being more or less completely repaired during the subsequent development. Thus a disturbing agency exists, so that the normal number of 14 joints is often departed from, though it appears to be really natural for this species. Bateson has also pointed out that when the normal number of articulations is not present, the relative proportions of joints 3 and 4 are much disturbed. It is, however, probable that the increase in number of the joints takes place by division of the third or third and fourth joints following previous growth thereof, as in Termitidae; so that the variations, as was suggested by Bateson, may be due to mutilation of the antennae, and consequent incompletion of the normal form of the parts from which the renovation takes place; growth preceding segmentation—in some cases the growth may be like that of the adult, while the segmentation remains more incomplete. In the young the forceps of the two sexes differ but slightly; the form of the abdominal rings is, on the contrary, according to Fischer, already different in the two sexes in the early stage.