TRAN SAC TIONS OF THE ROYAL MICRO- 
SCOPICAL SOCIETY. 
DESCRIPTION OF PLATES III & IV, 
Illustrating Mr. Whitney’s paper on the Metamorphosis 
of the Tadpole. 
PLATE III. 
Fig. 
1. — The young tadpole (enlarged view) within the capsule of the egg. 
2. — The tadpole (enlarged view) twenty-four hours after birth, exhibiting 
nostrils, mouth, suckers, and external gills. 
3. — The tadpole, life size, as seen by the naked eye, on the fourth or fifth 
day after birth, with the outer gills in full development. 
4. — The young tadpole (enlarged view), exhibiting the outer gills, with the 
digital-like tufts of the incipient inner gills, and the pair of minute 
tubes below the heart, which are the incipient lungs of the future 
frog. 
5. — The tadpole, life size, as seen by the naked eye, when the outer gills 
are disappearing. 
6. — The tadpole (enlarged view) with the outer gills nearly removed ; the 
operculum closed on the right side, but permanently open on the left ; 
the digital tufts enlarging. 
7. — Exhibits the crests of the inner gills in the more advanced stage, and 
the progressive development of the lungs at the same period. 
8. — Simple loop of blood-vessel as seen in the second stage of the inner 
gill (fig. 12), and the tortuous shapes afterwards seen in the crests 
of the third stage. 
9. — Enlargement of the vessel connecting the afferent and efferent trunks 
of the inner gill. 
10 — “The waning tadpole and incipient frog.” 
11. — View of the lungs as seen on one occasion through the back of a tad- 
pole. 
PLATE IV. 
12. — Internal gill of the tadpole, in its second stage. 
13. — Internal gill, fully developed, exhibiting the crests and vascular system. 
14. — The vascular connection of the external with the incipient internal 
gills. 
15. — Exhibits the lungs of the young frog, with the right lung in a state of 
vascular injection. 
16. — The heart, systemic arteries, pulmonary arteries and veins, and lungs 
in the full-grown frog. In the right hand figure the heart is turned 
up to show the junction of the pulmonary veins, and their point of 
entrance into the left auricle. 
