Discovery reports (1959) Discovery reports discoveryreports29inst Year: 1959 DEVELOPMENT AND GROWTH 335 post larval. From December onwards there are, in Fig. 15, still slight indications of three size groups and it is possible that a small part of the population does not spawn in the third spring but lives to spawn in the spring of the fourth year. The males of over 30 mm. in December carry ripe spermato- phores, and in the next two months an increasing number of undoubted i-year group males attain sexual maturity until, by March, practically all those over 25 mm. have reached the mature con
Discovery reports (1959) Discovery reports discoveryreports29inst Year: 1959 DEVELOPMENT AND GROWTH 335 post larval. From December onwards there are, in Fig. 15, still slight indications of three size groups and it is possible that a small part of the population does not spawn in the third spring but lives to spawn in the spring of the fourth year. The males of over 30 mm. in December carry ripe spermato- phores, and in the next two months an increasing number of undoubted i-year group males attain sexual maturity until, by March, practically all those over 25 mm. have reached the mature condition. On the other hand, during these months all females, including those over 30 mm. in length, have immature ovaries. Thus it is not possible to be certain whether these larger size groups are made up of animals that have grown more rapidly and the males have become sexually mature rather early, or whether they represent a small part of the population having a three-year cycle. Considering only those males which clearly belong to either the o-year group or i-year group the time taken to reach various degrees of maturity can be determined. The period of adolescence, that is the period during which the reproductive system is still developing (Bargmann's stages 1-5), lasts SHIlHBtB OCIOlSIl NOVEMBEK DECEMBEB MNUA«Y |EO«U»«» Fie i Monthly percentage length frequencies of E. triacantha. The number of specimens measured in each month is shown at the top. The pecked lines divide the population into year groups. These groups have been used m preparmg the growth curve, Fig. 16. from April to about the following November. During this and the next month an increasing number of males are found with imperfect spermatophores in the spermatophore sacs or ejaculatory ducts, and using Bargmann's criteria, these can be considered as having entered the adult phase. Durmg January and February a large proportion are found with mature spermatophores m both the spermato- phore sacs and th
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