510 EDEMA FOLLOWING NEPHRECTOMY 



Larvae of 5.5 to 7 mm. in total length are in the proper develop- 

 mental stage for successful extirpation of the pronephros and Wolf- 

 fian ducts. Shghtly older larva; (7 to 8 mm.) give fair results but 

 are not so easily handled as the younger stages. All extirpations 

 were performed under the binocular microscope with a blunt dis- 

 secting needle and a razor-edged, spear-head needle. The larvae 

 were narcotized with chloretone. 



The glandular portion of the pronephros in larvae of 5.5 to 7 mm. 

 in length shows very clearly as a small rounded elevation or nodule, 

 just caudal to the gills, on either side of the head. This elevation 

 represents the position of the coiled pronephric tubule^ with its three 

 nephrostomes which open into the coelomic cavity. The Wolfhan 

 ducts extend caudad and lie just ventral and medial to the edge of 

 the heavy band of musculature or myotomes. In favorable speci- 

 mens, with good illumination, the exact location of the Wolffian duct 

 is represented by a very faint line in the position just described. The 

 ducts in the later stages open dorsally into the cloaca. The operation 

 of removing the pronephros or its duct is simple and the wound closes 

 within an hour or two. 



Total Nephrectomy. 



The glandular portion of the pronephros was removed on both sides 

 of the body from 110 larvae. In many of the smaller larvie of the 

 group, i.e. in those measuring 5.5 mm., it was observed that the Wolf- 

 fian ducts had not yet opened to the exterior. The larvae, appro- 

 priately controlled, were left in well aerated water over night. On the 

 following morning, examination showed all the larger 7 mm. larvae to 

 be edematous. The edema in its incipient stages appeared chiefly 

 as a swelling of the submaxillary lymph sinus. 



20 hours after the operation, 16 larvae showed marked edema. 

 5 hours later 36 were edematous; at the end of 36 hours, 97 larvae 

 showed a typical edema. The few larvae which remained normal 



2 Field, H. M., The development of the pronephros and segmental duct in 

 amphibia, Bull. Mus. Comp. Zool., 1891, xxi, 201. Huber, G. C, On the mor- 

 phology of the renal tubules of vertebrates, Anat. Rec, 1917, xiii, 305. 



