The Development of Pieces of Diemyctylus Embryos. 103 

 Abstracts of the Communications, Pacific Coast Branch. 

 Sixteenth meeting. 



San Francisco, California, February 10, 1917. 

 64 (1242) 



The development of pieces of diemyctylus embryos. 

 By S. J. Holmes. 



[From the Department of Zoology, University of California.] 



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 larvae. In embryos cut in two just behind the gill region 

 the posterior part which was kept alive for some months under- 

 went 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. 



