Observations and experiments on spontaneous rhythmical behavior in the chick embryo☆

[摘要] Majorcharacteristicsofmotilityinchickembryosaredescribedfromitsbeginningatstage21(312–4days)tostage33(8days).Thefirstexteroceptivereflexescanbeelicitedatstage31,thatis,312–4daysafteronsetofmotility.Duringthisperiodallmotilityisself-generatedinthecentralnervoussystem.Extirpationofcervical,brachial,orthoracicsegmentsofthespinalcordatearlystagesdoesnotprecludemotilityinisolatedparts.Hence,partsofthespinalcordarecapableofautonomousmotility.Theearlybehaviorupto9–10daysisrhythmical;activityphasesof5–15secondsarefollowedbyinactivityphaseslastingfor30–60seconds.Kymographrecordingsoftheperiodicityinnormalembryosandinisolatedpartsshoweddifferencesinthetimepattern.Theactivityandinactivityphasesofisolatedpartsaremoreregular,andtheyarecharacterizedbyahigherpercentageoflongeractivityandinactivityphases.Thehypothesisisadvancedthattheperiodicityofthemotilityofnormalembryosresultsfromasuperimpositionofashortercycleoriginatinginthebrainoveralongercycleintrinsicinthespinalcord.

[学科分类] 生物科学（综合）