ON THE DUCTLESS GLANDS. 295 
parathyroidectomy. In some of these parathyroid tissue was found 
which had been overlooked at the operation ; but it is important to note 
that in a few instances the animal] died shortly after the operation, 
although two parathyroids were left intact. 
It has been frequently stated that parathyroidectomy is not only 
essentially fatal, but that death occurs more rapidly than when the thyroids 
are removed in addition, and various hypotheses have been put forward 
to explain this phenomenon. In the present series of experiments death 
occurred earlier on the average with the complete operation than when 
parathyroidectomy alone was done, and in most of these cases the 
symptoms were those of violent tetany. 
The experiments of Vincent and Jolly on the rabbit were few and 
inconclusive. In one respect our experiments entirely bear out.the con- 
clusions of the majority of workers on these animals—namely, that the 
animal dies in a few days if the whole apparatus be removed, thyroids 
and parathyroids together, but that it may survive for weeks or 
months if one or both of the external parathyroids be left in situ. 
Whether the animals may suffer from chronic symptoms _ re- 
sembling those of myxcedema in the human subject, cannot at present 
be certainly decided. It may be definitely stated, however, that no such 
chronic symptoms are noticeable after a period of three months. One 
rabbit, in which an attempt was made to extirpate thyroid and para- 
thyroids in toto, survived forty-five days without symptoms, and was then 
killed. But at the postmortem examination shreds of glandular-looking 
tissue were found in the former situation of the external parathyroid, and 
these on microscopical examination showed distinctly the first stages 
of transformation into thyroid tissue. Nearly all the portions of para- 
thyroid tissue revealed minute cleft-like spaces. In other portions of the 
tissue small rounded spaces, lined by a regular circle of cells, were to be 
seen, and in still other regions, especially at the edge of the parathyroid, 
were typical large colloid vesicles. 
In another rabbit, which died forty-three days after removal of the 
thyroid with both external parathyroids left in situ, no changes had 
occurred in these glandules. It is tempting to suppose that it is precisely 
these changes in the parathyroids left behind which make a prolonged 
survival possible. 
» Changes in the pituitary corresponding to those described by 
Herring after thyroidectomy have been noted in the case of the dog after 
parathyroidectomy. This may indicate a functional relationship between 
parathyroid and pituitary. 
Adrenals.—Dr. Young finds that, although on releasing ligatures 
which have been placed round the adrenal vessels there is a distinct rise 
of blood-pressure, yet during the period that the ligatures are applied 
there is no appreciable fall of blood-pressure. This is the case even after 
the lapse of several hours, with the blood from the adrenals absolutely 
excluded from the circulation. 'These experiments were performed upon 
dogs. Strehl and Weiss obtained a temporary fall on clamping the 
adrenal veins of the rabbit. 
Paraganglion aorticum.—Mr. McKenty and Professor Swale Vincent 
have succeeded in displaying the ‘ paraganglion aorticum’ in several 
animals by the method of Stilling and Kohn, and a detailed microscopical 
pty of this and kindred structures is being carried out at the present 
ime. 
