XX I] DEVELOPMENT 557 



Bombinator the vasa efferentia apparently open directly into the 

 archinephric duct in front of the kidney. These vasa efferentia, 

 like those of Lepidosiren (see p. 508) must be regarded as modifica- 

 tions of a conjoined vas efferens and kidney tubule which constituted 

 the original connection between testis and kidney. 



Lying on the ventral surface of the kidney near its inner edge is 

 an elongated body called the adrenal body (14, Fig. 276, A). This 

 organ is found under various forms in most Vertebrates; it has 

 been recently shown to be derived from a peritoneal furrow which 

 becomes shut off from the general coelom and loses its cavity, 

 forming a solid rod of cells. Experiments made on higher animals 

 and the observation of cases where it is attacked by disease, show 

 that the adrenal bodies, like the thyroid, produce an "internal 



FIG. 277. Tadpole of Eana esculenta, Lin. taken near St Malo x 1. From 



Boulenger. 



1. Dorsal fin. 2. Tail showing myotomes. 3. Hind-limb. 



secretion." The substances poured into the blood by both these 

 organs are essential to the proper conduct of metabolism, that of 

 the adrenal bodies being stimulating to the muscular tissues in 

 particular. 



The eggs develop entirely outside the body, and there is a large 

 thin-walled swelling of the oviduct in which the ripe eggs accumulate 

 just before being discharged. The male clasps the female round 

 the waist and remains in this position sometimes for weeks, uttering 

 loud croaks at intervals until the eggs are discharged. When 

 the eggs are discharged he emits the spermatozoa on to them. The 

 croaks are made by pumping the air from the lungs through the 

 glottis into the pharynx and vice versa. The pharynx has in Rana 

 esculenta two side pouches, the vocal sacs, which become inflated 

 with air. It is thus possible for this frog to croak when under 

 water. 



The development is in many respects different from that of 

 Urodela. Soon after the young are hatched they acquire, it is true, 



