Diversity in die Scutes of Clieloiiia, 47 



ao that most of the eggs were placed in the ground. Later it was 

 found that a proper incubator would yield better results than the soil 

 of the island. 



The incubator used was very simple, it consisted of a box with 

 four shelves, each holding 72 eggs. The shelves were large enough 

 for each egg to be entirely surrounded by a small amount of sand. 

 The light cushions of sand around and above the eggs served to main- 

 tain a comparatively uniform condition of humidity, while at the 

 same time permitting the eggs to expand in size without crowding. 

 This growth of the eggs, by the tilliug out and distension of the 

 shell, commonly occurs to a greater or less extent during the develop- 

 ment of the embryo. The sand was spriid^led with water as often 

 as necessary. It was not necessary to apply artificial heat since 

 the chief problem was to keep the temperature as low as it would 

 ordinarily be at the depth of the natural nests. To obtain fairly 

 uniform conditions of humidity and temperature, this box w^as placed 

 within another box so much larger than the first that there was the 

 space of 6 inches between the side walls (except on one side), the 

 bottoms and tops, respectively, of the two boxes. The space between 

 the two boxes was packed with moist sand. On the fourth side the 

 inner box opened by a thick door containing a six-inch thickness 

 of sand. Outside of this was the door to the outer box. Thus the 

 inner chamber was well protected from such rapid changes of tem- 

 perature or moisture as might take place outside. At the same time 

 it could readily be opened at any time and one or more eggs removed 

 without disturbance of the others. If the temperature seemed rising 

 too high, moistening the outside of the box and the top layer of sand 

 would, through evaporation, lower the temperature within a day ; 

 or, if necessary, the doors could be left open, when the evaporation 

 would low'er the temperature very quickly. In this way it was not 

 difficult to keep a tolerably uniform temperature of 26° to 28° C. 



The observations to be given below wall at least suggest that the 

 eggs of the loggerhead sea-turtle would lend themselves well to 

 experimental study, by varying the conditions of incubation. Dur- 

 ing the past summer (1905), however, the experiments were made 

 subservient to the obtaining of embryological material and it can- 



