DEVELOPMENT OF KIDNEYS AND FAT-BODIES IN THE FROG. 149 



part of a urinary tubule, and while recognising the need for further 

 evidence,, is inclined, on the strength of this one doubtful instance, 

 to regard such a connection as occurring generally in the Anuran 

 kidney. 



The presence of numerous nephrostomes in the kidney of the 

 adult frog, though conclusively proved by Spengel's description, has 

 not yet, in this country, obtained general acceptance ; and in the 

 most recent work on the anatomy of the frog, the English translation 

 of Ecker's well-known book, the editor states that after careful 

 examination of sections, teased specimens, and fresh and injected 

 kidneys, he was unable to find any trace of the nephrostomes.* 



Under these circumstances, we have thought it well to examine 

 carefully the structure of the kidney in adult and in young frogs, as 

 well as in tadpoles. 



In the kidney of the adult frog we find the nephrostomes present 

 in large numbers, exactly as Spengel describes them. Fig. 7 repre- 

 sents a transverse section through the kidney of an adult male frog, 

 taken not very far from the anterior end. The dorsal half of the 

 kidney is formed mainly by the large collecting tubes K T. In the 

 ventral half lie the narrower and much convoluted " third sections " 

 of the urinary tubules, K R, and also the Malpighian bodies, K G. 

 On the ventral surface, which is covered with peritoneum, three 

 nephrostomes are shown, each commencing with a mouth, E A, 

 opening into the body cavity, and surrounded by a slightly raised 

 lip, which leads into the short nephrostomial tubule, E. The walls of 

 the tubule are composed of a single layer of small cubical epithelial 

 cells with pigmented walls, each cell bearing a long flagellum, which 

 lies in the tubule with its free end directed inwards. Round the 

 mouth of the tubule the flagella form a ring projecting into the 

 cttlom. 



We have found no difficulty in seeing these nephrostomes in any 

 good series of sections of frog's kidney, and entirely fail to under- 

 stand why they have been overlooked by other observers. They 

 are not present in every section, but an examination of half a dozen 

 consecutive sections is certain to show one or more. Fig. 7 is not 

 drawn from a single section, but from four consecutive ones, as a 



* "The Anatomy of the Frog," by Dr. Alexander Ecker; translated with numerous 

 annotations and additions by Dr. J. Ilaslam. Oxford, 1889, p. Xid. 



