64 THE ROYAL SOCIETY OF CANADA 
2. TE PARATHYROIDS. 
The frog has usually two parathyroids on each side, sometimes 
three. They are in much closer anatomical relation to the ventral 
branchial body than to the thyroid. They are not difficult to see with 
the naked eye; but their study is facilitated by means of serial sections. 
They are represented by small oval or rounded corpuscles lying in front 
of the common carotid artery (Pl. I, fig. 1, pthyr.) There is a fibrous cap- 
sule (PI. III, fig. 3) surrounding each glandule which has a very compact 
appearance. It consists of closely packed, deeply staining cells of which 
some of the nuclei appear spindle-formed. In some cases the cells are 
longish and so disposed that they appear to describe spiral turns. The 
cell outlines are very distinct even under a low power (Pls. III and IV, 
figs. 3 and 4). Some of the cells appear to be vacuolated. The cells 
vary greatly in shape and may be oval or irregularly cubical. 
Historical. 
Ecker! was the first to observe the parathyroids, but considered 
them as representatives of the thymus. Later Leydig? described them 
in relation to the ventral branchial body and said that with it they 
represent the thyroid. Gaupp® suggested that the bodies described by 
Leydig are the parathyroids and ventral branchial bodies and this seems 
quite evident on looking at his figure.* 
For some years the parathyroids were called “ Nebenschildrtisen,”’ 
which led to their being confused with accessory thyroids. Maurer’ 
elucidated this matter and recognized their homology with the glandule 
parathyroidem which Sandstrém discovered in 1880 and® described in 
man and other mammals. Apparently only the external glandule was 
noted by Sandstrém. 
In 1891 Gley? in his preliminary note on the effects of extirpation 
of the thyroid in the rabbit describes the bodies as “glandules thyrüi- 
diennes,” and in 1901 put forward a theory of functional relationship 
between thyroids and parathyroids. This has received support from 

* Wagner’schen Handwortebuch der Physiol. Vol. 4, 1853. 
? Anat. Hist. Untersuch uher Fische u. Reptilien, Berlin, 1853. 
* Ecker, Wiedersheim, 1901. 
sshoe!- city Tarte 5: 
° Morph. Jahrb. Vol. 13, 1888. 
5 Lakare-férenings Férhandlinger, Vol. 15, 1880. 
7 C.R. Soc. de Biol., 1891, p. 843. 
