THE DEVELOPMENT OF THE KIDNEYS AND FAT- 

 BODIES IN THE FROG. 



By A. Milnes Marshall, M.D., F.R.S., Beyer Professor of Zoology 



in the Owens College; and 



Edward J. Bles, of the Owens College. 



[With Plate X.] 



In the present paper we do not propose to attempt a complete 

 description of the development of the urinary organs in the frog, but 

 shall confine ourselves to certain points which have recently engaged 

 our attention. Of these, the more important are : (1) the mode of 

 formation of the head kidney and its duct ; the structure and relations 

 of these parts during the successive stages of larval life ; and the 

 degenerative changes which they undergo about the time of the 

 metamorphosis : (2) the development of the tubules of the Wolffian 

 body : (3) the development of the nephrostomes and their anatomical 

 relations during larval life and in the adult condition : (4) the early 

 development of the fat-body. All our observations were made on 

 specimens of Rana temporaria, and are based partly on dissections, 

 partly on the examination of sections in the three principal planes, 

 transverse, sagittal, and horizontal. 



I. The Head Kidney and its Duct. 



1. Historical Account. — Goette* gives a careful account of the 

 early stages in the development of the head kidney and its duct in 

 Bombinator. He describes the head kidney as arising in the first 

 instance as an outward fold of the somatopleuric mesoblast at the 



* Goette, "Dio Entwick<:lun«Hgcschiclitc dor Unke," 1875, pages 819-828, and 

 plates vi., vii., xiii., and xxii. 



