62 Journal of the Mitchell Society [September 



four were opened and found to be in blastopore stages. One of these 

 is shown in fig. 27. It is to be noted that this egg, although retained 

 for a month, had not passed beyond the blastopore stage, and it 

 seems reasonable to suppose that the development of the three un- 

 opened eggs was about the same. The three unopened eggs were 

 placed under incubation conditions. Figure 10 was made from one 

 of the eggs from this clutch, artificially incubated for forty-eight 

 days. Figure 11 is a drawing of a specimen from a non-retained 

 egg which was incubated for forty-three days. A comparison of 

 these two embryos shows that no unsatisfactory results came from 

 such retention. In order to determine how long they could be forced 

 to retain their eggs, turtles collected early in June were kept in 

 tanks of water without sand until the latter part of July, when 

 some of them, at least, laid their eggs in the water and presumably 

 ate them, for the only evidence of such deposition was the empty 

 egg shells. Dissections of a number of individuals at a later time 

 showed no traces of eggs. 



Artificial Incubation 



Up to date, efforts to incubate artificially the eggs of turtles and 

 terrapins have not been very satisfactory, although several success- 

 ful attempts have been reported. One of these cases is related by 

 Pease (1910), who carried home some newly laid eggs to show the 

 children. These eggs were carelessly left in a tin box on the pantry 

 shelf and in due time they hatched. Neither the species nor any 

 other detail was given. Another plan, used commercially, is reported 

 by Moulton (1914) who states that the eggs of the diamond-back 

 terrapin are collected from the sandpiles in which they are laid, 

 placed in boxes of sand, and sprinkled with water weekly until they 

 hatch. Little data is given. Hochstetter (1906) mentions the arti- 

 ficial incubation of some fifty eggs for embryological purposes, by a 

 method similar to that reported by Moulton. 



Before any of the papers mentioned above had come to the knowl- 

 edge of the writer, the following experiments had been successfully 

 carried out. The first effort of the writer to incubate Chelonian 

 eggs, artificially, was made in the summer of 1918 at Trinity Col- 

 lege, Durham, North Carolina. Four eggs, secured from a potato 

 hill near Farmville, Virginia, about the middle of August, were 



