The development of pieces of diemyctylus embryos

Abstract

In a series of experiments performed on pieces of embryos of the newt Diemyctylus torosus care was taken to eliminate all sources of infection. The jelly surrounding the embryos was washed in a solution of mercuric chloride and then in sterile distilled water and transferred to sterile Ringer's solution in which the embryos were liberated. The embryos were then cut by means of a sharp razor into pieces of various sizes which were kept in sterile Ringer's solution. Even relatively small pieces showed developmental changes, and pieces from the neck region sometimes developed outgrowths which very closely resembled the gill filaments of the normal larvæ. In embryos cut in two just behind the gill region the posterior part which was kept alive for some months underwent a course of development strikingly like that of the normal embryo. The outgrowth of the tail, the development of the transparent median tail fin or keel, the formation of pigment cells, and the differentiation of tissue cells in general occurred in a perfectly normal manner so far as could be observed. These pieces increased in size, doubtless through the absorption of water, and became relatively transparent as the yolk granules in the cells were assimilated. In nearly all of these pieces the heart was entirely absent. Correlated with this was a complete absence of peripheral blood vessels. In the controls these were well developed and blood could be seen rapidly streaming through them, but, although the pieces developed far beyond the stage at which these blood vessels normally appear, they showed at no time any trace of these peripheral vessels. Sections, however, showed that the aorta and some of the larger veins were more or less imperfectly developed.