294 REPORTS ON THE STATE OF SCIENCE. 
of the medulla of the adrenal body and the question of its relation to 
other similar tissues in the body. 
Thyroids and Parathyroids.—Mrs. Thompson reports that all the 
evidence collected from a study of the thyroids and parathyroids through- 
out a wide range of the animal kingdom supports the view held by 
Vincent and Jolly, and by Forsyth—namely, that thyroids and parathy- ° 
roids are not separate and independent organs, but are very intimately 
related. Within the thyroid of elasmobranchs are small, solid masses 
of cells, partly epithelial, partly adenoid. ‘These, so far as we are aware, 
have not been previously described. In Teleosts there appears to be 
nothing corresponding to the parathyroid. The cells lining the thyroid 
vesicles are almost flat. In Amphibians the parathyroid is not in intimate 
relation with the thyroid. In Reptiles thyroids and parathyroids are 
anatomatically separate organs, but the parathyroid in some instances 
possesses distinct lumina, and the post-bronchial body secretes colloid. 
in Birds we frequently find large areas of the thyroid devoid of colloid 
vesicles (confirmatory of Forsyth). In Mammals there is much more 
intimate relationship between the parts of the thyroid apparatus than 
in the lower animals. ‘The cells lining the vesicles are apparently of 
the same character as those accumulated in varying amount between 
the vesicles, which do not differ in any essential respect from those form- 
ing the parathyroid glandules. Many of the masses of intervesicular cells 
are indistinguishable from parathyroids. ‘The internal parathyroid is 
frequently in direct tissue continuity with the thyroid and every kind of 
transition form exists. Parathyroid seems only to require colloid spaces 
in its interior in order to constitute itself thyroid, and this occurs in the 
human subject under certam pathological conditions. But thyroid 
and parathyroid are to be looked upon as structures of somewhat different 
embryological origin, which are totally distinct in the lower vertebrata, 
although coming into very intimate anatomical and physiological relation- 
ship with each other in the Mammalia. In this latter group they form, 
in fact, one apparatus. 
Vincent and Jolly found that in the cat a parathyroid left behind after 
thyroidectomy changed its structure so as to approximate to that of 
thyroid. Inthe dog Dr. Halpenny has found similar, but more marked, 
changes in a parathyroid left behind after removal of the thyroid, and he 
also describes a case (see below) of the same kind of transformation in the 
rabbit. 
Without denying that parathyroidectomy may be in itself fatal, 
Dr. Halpenny’s experiments justify him in adopting the attitude 
of Vincent and Jolly that the operation is so supremely difficult 
(indeed, in the majority of cases, impossible) that the positive evidence 
on this point is far from convincing. It is certainly true that 
in many cases, when one performs the operation of total parathy- 
roidectomy, doing as little damage as possible to the thyroid itself, the 
- animals die quickly and with severe symptoms. But it is also the case 
that in many instances, when the operation has apparently been just 
as completely performed, the animals do not appear to suffer. This 
position has been reached after a large number of experiments, in many 
of which a complete histological examination was made of everything 
which was removed at the operation, and of all adjacent structures which 
were found on postmortem examination. ‘This has involved the cutting 
of a large series of sections through the thyroid of animals which survived 
