6 TADACHIKA MINOURA 



inserting anything on the membrane; and in still other cases 

 the control eggs were untreated. 



b. Examination. The operated eggs were removed from the 

 incubator at different intervals after operation for examination. 

 Such intervals varied from one day to tune of hatching. In 

 spite of the greatest care, in some experiments many eggs became 

 infected and failed to develop further. Observations and meas- 

 urements were made upon the grafts and embryos in the living 

 state; they were then preserved for further examination. For- 

 mol-Zenker was usually employed as a fixing agent, Bouin's 

 fluid in some cases. Many of the preserved embryos were 

 photographed after dissection. I am greatly indebted to Doctor 

 Bartehnez for his generosity in permitting me to use the dark 

 room in the Anatomy Department for photographing the ma- 

 terials, and to Dr. Marion Hines and Mr. K. Toda for their 

 kind assistance and advice in making the photographs. 



3. Growth of grafts 



a. External observations. When an operated egg is opened for 

 examination, if the grafted piece is growing or alive, a white 

 mass will be found on the chorio-allantoic membrane, to which 

 umbihcal blood-vessels are connected (figs. 1, 4). The mass is 

 somewhat translucent and white or yellowish or more or less 

 rosy in color. The grafts in general grew much more readily 

 toward the inside than the outside of the membrane (figs. A, 5). 

 In several instances a marked convergence of blood-vessels to 

 the graft was noticed. Vascular connection is established with 

 the grafts as early as twenty-four hours after operation. 



The amount of growth which has occurred in the grafts is of 

 course different in different cases depending upon the following 

 factors: 1) duration of the graft; 2) age of the embryo at the 

 time of the operation; 3) degree of vascular connection with the 

 grafts. Under the most favorable conditions, the grafted masses 

 attained a considerable size, 10 mm. in diameter and several 

 millimeters in thickness. In the majority of cases, however, 

 they varied from 3 to 7 mm. in diameter, that is, the original 



