The Relative Growth of Parts in Palaemon Carcinus

IT has been suggested (Huxley, 1927; Shaw, 1928) that in various animals, such as some Crustacea which show disharmonic growth, there exist growth centres correlated with the active growth of specific organs or regions. Also that the growth of neighbouring parts is correlated with the growth of the heterogonic organ. In Maia squinado (Huxley, 1927) and Inachus dorsettensis (Shaw, 1928) the growth of the appendages posterior to the heterogonic pereiopod was increased and of those anterior decreased. In these previous cases, however, the heterogonic organ was the 1st pereiopod; therefore the appendage whose growth decreased was the 3rd maxilliped, which (a) is very small and (b) belongs to a different type of appendage. The result might thus be accidental since the appendage in each case was so small; if not, the result might be correlated with the different type of appendage, or it might be due to its position on the main axis of the body. In Palaemon carcinus the heterogonic cheliped is the 2nd pereiopod, hence the main object of the present experiment was to determine whether the growth of the pereiopod anterior to the cheliped is decreased.