222 PAULINE H. DEDERER. 



over, cell proliferation from each piece was more abundant. 

 Cultures grew in media containing no dextrose, or with varying 

 amounts of dextrose up to 2 per cent. Media containing 0.5 

 per cent, gave the best results. The cultures grew equally well 

 with 80 per cent, of Locke's solution in place of sea water. Good 

 results were obtained with 80 per cent, of Locke's solution and 

 20 per cent, of chicken bouillon substituted for the fish bouillon, 

 although not so many cultures grew. Pure egg albumen and 

 dilutions of this added to the normal medium likewise proved 

 successful. 



Several cultures which contained tissue from both chick and 

 Funduhis embryos were made in Locke's solution, chicken 

 bouillon and dextrose. These were kept in the incubator at 

 39 C. and at the end of 48 hours the explants showed equally 

 good outgrowths. 



Cultures were usually prepared in the afternoon, and by the 

 following morning growths in the form of membranes had formed, 

 though sometimes this did not occur until the second day, es- 

 pecially when a dilution of 20 per cent, sea water was used. 

 The embryos were 7, 10, 14 and 15 days old (just before hatching) 

 but the age made no apparent difference in the growth from the 

 explant. 



GENERAL CHARACTERISTICS OF THE CULTURES. 



Examination of the cultures shortly after explantation usually 

 showed a few isolated mesenchyme cells, which soon began to 

 migrate outward on the cover-slip. The ectoderm cells in the 

 region of the cut edges rounded up into more or less spherical 

 bodies. After several hours typical cultures revealed a mem- 

 branous outgrowth of ectoderm from one or more regions of the 

 explant, and beyond this an area of mesenchyme cells, isolated, 

 or forming a reticulum upon the under surface of the cover-glass 

 (Fig. i). Nerve fibers, projecting freely into the fluid along the 

 coverglass, were often present in abundance. Pigment cells and 

 yolk-filled cells from the digestive tract (Fig. 7) were also com- 

 mon. No outgrowth of muscle cells was observed. 



A renewal of the fluid medium was not attempted in any of 

 the cultures. The oldest healthy cultures were ten days old, 



