Eighth Stage Research Articles

Erikson's theory of human development as it applies to the aged: wisdom as contradictive cognition.

Erikson’s theory of human development is discussed with particular emphasis on the feasibility of attaining the eighth stage. The question is raised as to whether most elderly indiv

Reproduction, growth and bionomics of Dynamene bidentata (Crustacea: Isopoda)

Laboratory and field investigations show that there are five distinct marsupial stages and eight post‐marsupial stages in the development of the isopod Dynamene bidentata (Adams). Extensive sexual dimorphism is apparent, beginning at stage 6, and females undergo extensive tissue reduction at the moult to the eighth stage. Young stages inhabit and feed on intertidal algae, and the non‐feeding adults (stage 7 and 8 females, and stage 8 males) shelter in crevices or empty barnacle tests. Average brood numbers are fairly high (c. 90) and the average marsupial mortality rate is about 36%. Release of young takes place in May/June, after which the females die, and a resident population of males remains in the crevices to be joined by newly maturing females and males from August onwards each year. The occurrence of two breeding seasons in males, but not in females, explains how the sex ratio of males to females as they leave the algal habitat (1:9) is about half the ratio of males to females in the reproductive habitat (1:4).

DESCRIPTIONS OF THE LARVÆ OF CERTAIN TENTHREDINIDÆ

Eighth stage.—Head shining black, yellowish punctured around the mouth, antennæ yellowish; eye and jaws black; width, 1.8 mm. Body ochreous yellow, 6-annulate with irregular quadrate sub-dorsal (two per segment) and lateral (one per segment) black spots, confluent on joint 13; sub-ventral ridge faintly discolured; anal plate blackish. No white secretion. The larvæ do not feel in this stage, but seek for soft wood in which they bore their galleries for pupation.