1. The cause of the rhythmic contraction of the ventricle lies within the ventricle itself.

2. The cause of the rhythmic contraction is not a single, localized, co-ordination centre; the co-ordination mechanism, whatever it may be, is present in all parts of the ventricle.

3. The integrity of the whole ventricle is not essential to the coordinated contractions of a part of the ventricle.

4. The apex of the mammalian heart possesses spontaneous, rhythmic contractility.

5. Assuming that the general belief in the absence of nerve cells from the apical part of the ventricle is correct, these experiments demonstrate that nerve cells are not essential to spontaneous, long-continued, co-ordinated contractions of the ventricle.

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