Nachdruch verboten. 

 Uebersetzungsrecht vorbehalten. 



Observations on the Development of the Excretory 

 System in Turtles. 



By 

 Emily Ray Gregory. 



With Plates 45—50. 



The researches described in the following thesis were carried on 

 at the Hull Biological Laboratory of the University of Chicago, under 

 the direction of Professor William Morton Wheeler whose sug- 

 gestions have been most valuable. To him and to Dr. C. 0. Whit- 

 man, Head-Professor of the Department of Zoology, I wish to express 

 my deep appreciation of the kindness shown me and my sincere 

 gratitude. 



Material. 



Early in the spring of 1897 Prof. William Morton Wheeler 

 advised me to make a careful study of the development of the ex- 

 cretory system of the Turtle. For this purpose the late Prof. George 

 Baur gave me a number of embryos of Aromochelys and of Flaty- 

 peltis spinifer, preserved in alcohol. On sectioning these, however, it 

 proved that they were all too far advanced to show the origin of the 

 excretory system, and it was necessary to seek more material, 

 especially in the earliest embryonic stages. Through the courtesy of 

 Prof. Carl H. Eigenmann of Indiana University I gained access to 

 its Biological Station at Vawter Park, Indiana, on the north side of 

 Turkey Lake. My first visit was from noon of Friday, June 25th, 

 1887, until Monday the 28th. In this short time, with the help of 

 two of the students, I collected between three and four hundred eggs. 

 Of these I killed a few, some in chromic acid, and some in saturated 

 solution of corrosive sublimate. Packing the rest carefully in a basket 



