No. 515] 



THE AMERICAN TOAD 



057 



do so. A few days previous to this time, the tail has be- 

 gun to shrink and by the second day out of the water may 

 be completely absorbed. Meanwhile great changes take 

 place in the region of the head. The eyes become en- 

 larged and elevated; the larval beak or jaws are lost; the 

 mouth broadens and a tongue forms ; the gill slits close 

 and the lungs mature. The long coiled alimentary canal 

 shortens and differentiates into stomach and intestine. 

 The color changes from a jet black to a brownish tinge 

 with faint spots. The skin is yet perfectly smooth. All 

 of this growth, development and metamorphosis from the 

 egg to the completion of the toad may take place in thirty- 

 two days, or two hundred, as in the case of some kept in 

 the laboratory in a poorly fed condition. 



The following table is given to show the rate of growth 

 and development. 



Table I 



The weight given for the eggs is that previously de- 

 termined for those removed from the ovary. To weigh 

 the tadpoles, they were placed upon a glass slide covered 

 with filter paper which was moistened sufficiently to keep 



