AUTHOR'S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, AUGUST 11 
THE DEVELOPMENT OF THE THYREOID GLANDS OF 
BUFO AND THEIR NORMAL RELATION 
TO METAMORPHOSIS! 
BENNET M. ALLEN 
Department of Zoology, University of Kansas 
ONE PLATE (SIX FIGURES) AND ONE TEXT FIGURE 
In recent years much light has been thrown upon the influence 
of the thyreoid gland upon growth. Most striking are recent 
studies upon the influence that this gland exerts upon meta- 
morphosis in the amphibians. Gudernatsch (712) showed by 
experimental means that feeding thyreoid preparations of sheep 
to tadpoles of Rana greatly accelerated their metamorphosis. 
This experiment has been repeated by others (Swingle, ’18) and 
completely verified. In 1916 the writer was successful in re- 
moving the thyreoid-gland anlagen from young tadpoles, which 
were then reared to a period long after that at which meta- 
morphosis should normally occur, one tadpole being kept alive 
until fourteen months after the operation. In all successful 
cases there was total failure to metamorphose, although the 
hind limbs underwent a limited amount of growth and the fore 
limbs began to develop without, however, breaking through the 
skin. 
Hoskins and Morris (16) suecessfully accomplished the re- 
moval of the thyreoid gland in a similar way at the same time 
in Rana and Amblystoma. They had some difficulty in rearing 
the operated tadpoles, but were successful the following season. 
Their work was reported at the December, 1916, meeting of the 
American Association of Anatomists and again at the December, 
1917, meeting. 
In the spring of 1917 the writer repeated his earlier experi- 
ments upon Rana and also performed similar operations upon 
1Contribution No. 318 from the Department of Zoology, University of 
Kansas. 
489 
