20 



T. H. BURLEND, 



Embryo G. 



This embryo is sectioned somewhat obliquely, and so the proto- 

 vertebrae at the front of the body appear to overlap. 



About 4 mm. long. Stained in Boraxcarmine , sectioned, and 

 mounted the sections on 6 slides having respectively 60, 58, 60, 60, 

 60 and 45 sections. 



Body begins 1,4. 



In this embryo the first traces of the kidney groove on the 

 left side are at 3,4. After continuing as a groove for a few sections 

 it becomes a solid outgrowth: further back it tends to become twisted 

 and to project into a groove in the ectoderm. 



The duct begins about 3,49 and becomes indistinguishable 

 at 4,45. 



At times (viz. in 4,14 and 4,25) there seems to be a slight con- 

 nection between mesoderm and duct. 



The segments affected are : post, portion of VI, VII, VIII, IX 

 ant. half of X. The duct extends over the post, half of X, XI, XII, 

 XIII and 5 sections further back. 



On the right side the kidney groove begins at 3,7, extends as 



