TRANSACTIONS OF THE ROYAL MICROSCOPICAL 
SOCIETY. 
On the Changes which accompany the Metamorphosis of the 
Tadpole, in reference especially to the Respiratory and 
Sanguiferous Systems. By W. U. Whitney, Esq., 
M.R.C.S., &c. &c. 
(Read March 13th, 1867.) 
In a paper read on the loth June, 1861, I had the honour 
of submitting to the members of this Society a description of 
the general sanguiferous system in the tadpole, the tracing of 
which was rendered more complete and satisfactory with the 
aid of the binocular microscope, at that time a recent inven- 
tion. 
Those investigations, and the subsequent ones, were made 
with the admirable microscope possessed by my friend Mr. 
Fitzgerald, and to his manipulative skill, not less than to the 
goodness of his instrument, I am largely indebted. 
A more extended inquiry has had the advantage (1) of 
correcting an anatomical and physiological error into which I 
had unconsciously fallen, the cause, nature, and correction of 
which were explained in a communication to f The Intellec- 
tual Observer 5 for May, 1863 ; and {2) of directing investi- 
gation to the anatomical changes, in reference especially to 
the respiratory and sanguiferous systems, which accompany 
the metamorphosis of the tadpole from the form and functions 
of the fish to the shape and habitudes of the reptile. 
The fact that one creature possesses not less than three sets 
of respiratory organs, two of which are successively developed 
and then annihilated, could not fail to excite curiosity, 
though the difficulty of tracing the steps of the process by 
which these transitionary changes are accomplished appears to 
have been generally felt. The writer of the article, “ Batra- 
chia,” in the c Encyclopaedia Britannica,’ says, “ the change 
or conversion from external to internal gills is not satisfacto- 
rily described by physiological observers.” And this state- 
vol. xv. e 
