Ref ID : 6677
Henriette Herlant-Meewis; [Les lois de la Scissiparite chez Aeolosoma hemprichi (Ehrenberg)]. Revue Canadienne de Biologie 8:123-148, 1950
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Aeolosoma hemprichi is a small limicole Oligochaeta worm forming composite chains of two to six incompletely formed individuals, each one being composed of not more than six setigerous segments. When the stage of six segments is reached, a constriction takes place in the pygidium and another individual appears in the form of a pygidial bud. The latter grows up and when it possesses the six regular setigerous segments a bud is formed. Simultaneously the original zoid gives forth a second, then a third individual and so on. The living chain lengthens and breaks up automatically at the anterior end of the eldest one when the latter has accomplished its cephalization. In the course of the asexual reproduction of this worm, the author never noticed a true region of scissiparity breaking an individual into two sections each one containing a certain number of setigerous segments, as we observe generally in Naidimorphic Oligochaetes. The nutritional condition of the environment controls the length of the chain, the number of individuals in a chain becoming larger as the medium is richer in food supply. Short chains with slender and discolored individuals are the response to a poor nutritional environment. Temperature is an important factor influencing growth, but it is of no effect on the asexual reproduction modalities. A. hemprichi is a wonderful animal to study the kinetics of growth in Invertebrates. This essay shows that, in this worm, asexual reproduction is active and complies with rigid and definite laws. In this way quantitative datas of growth are easily available. These datas will permit to find out the influence of growth substances. We comtemplate experimenting along that live.