AGASSIZ’S WORK ON THE EMBRYOLOGY OF 
THE TURTLE. 
GERTRUDE C. DAVENPORT. 
Acassiz’s Embryology of the Turtle — the second volume in 
the series of Contributions to the Natural History of the United 
States of America (1857) — was for its time, and still remains 
in these days of refined histological technique, a beautiful and 
useful research. The scope of the book is broad. Stages in 
the development of the turtle are described, beginning with the 
most immature eggs in the ovary and continuing through many 
embryonic phases until the young turtle hatches out. 
In addition to the great contribution to embryological 
knowledge which this book brought, it also contained much 
information of a sort too often unobserved or omitted by 
embryological investigators of to-day; namely, the habits, 
especially the breeding habits, of the animals studied. 
Even to the present time we have almost no other printed 
accounts and none so complete to which we can turn for 
information in regard to the breeding time of and the number 
of eggs deposited by our commoner American turtles. Indeed, 
until Agassiz’s time, and even to-day, it is believed by many 
that turtles lay in the fall as well as the spring. By careful 
observation upon turtles kept in comparative freedom and upon 
those in a wild state, Agassiz found that turtles deposit eggs 
once a year, normally in the months of May and June, the 
time depending upon the kind of turtle in question. Moreover, 
he determined the age at which various kinds of turtles begin 
to lay eggs and the time necessary for their hatching. These 
are only a few of the many interesting and useful facts regard- 
ing the life history of the turtle which this volume contains. 
Agassiz’s studies of ovarian eggs likewise disclosed many 
new facts. For example, the period of growth of ovarian 
eggs was determined. Ovarian eggs develop in sets corre- 
sponding in number to that of each laying. From the size and 
appearance of these ovarian sets, Agassiz was able to say 
