Unco-ordinated contractions caused by egg white and by alternations in the cation ratio of the medium in the heart of the chick embryoin vitro

In May, 1932, some experiments were made in which fragments of chick embroys in primitive streak stages were explanted into crude white of egg as culture medium. The object was to study hæmatopoiesis, which occured in these explants (Murray, 1933). Only two of the cultures interest us here. Both were derived from embryos having pear-shaped areæ pellucidæ with primitive streaks but no head processes and each consisted of that part of the area pellucida of one side which lies opposite the posterior half or three-quarters of the primitive streak. Both cultures survived in the egg white and in each there was discovered, after two and five days incubation respectively, an area which contained actively contracting cells. The contractions were of small amplitude and there was no co-ordination between the cells. This activity persisted in one culture for 36 days. It was necessary to have some name by which this anarchic contractility could be designated; it resembled fibrillation, at least superficially, but it was thought best to avoid this term as the present phenomenon might prove entirely unconnected with fibrillation. The word "twitter", used as noun and verb, described the appearance rather well, and I have adopted it as a provisional name for this kind of activity.