598 
MR. E. C. BABER OR THE STRUCTURE OF THE THYROID GLARE. 
manner with colouring agents, he points out that the contents of the lymphatics show 
an entire absence of the phenomena of contraction observed in the contents of the 
vesicles. 
Observations. 
Mammalia. —A system of lymphatics, resembling in its general characters that 
described in the Dog, has been observed in the thyroid glands of other animals ( e.g., 
Kitten, Horse, Rabbit) by means of injections by the method of puncture. The extent 
of distribution of the network and the minuteness of its ramifications appear to vary 
in different animals. 
The homogeneous or granular contents of the lymphatics have been observed in the 
same vessels in the thyroids of other annuals (e.g., Horse, Sheep). This material occurs 
both in injected and in uninjected specimens. The quantity varies much in different 
glands of the same species of animal, it being sometimes present in large quantities 
and at other times being apparently entirely absent. With a view of ascertaining 
whether the occurrence of this material in the lymphatics was peculiar to either sex, 
or to any particular age, I examined the thyroids of Dogs of various ages in both sexes, 
but, as might be expected, without any definite result. It appeared to be present or 
absent regardless of the sex or age of the animal. The margins of the coagulated 
content of the lymphatics undoubtedly do not present the indented appearance seen 
in the vesicular contents, but this is, I imagine, simply due to the absence of epithelial 
cells, from which drops of clear fluid could exude (see above, pages 591 and 592). 
Aves. — In the thyroid gland of Birds, on the contrary, I have been unable to inject 
any system of lymphatics. My observations on this point are as follows :—On injecting 
the thyroid gland of a Pigeon by the method of puncture with Berlin blue, it swells 
up, and the injection is seen running in the jugular vein with which the gland is in 
close apposition. (It will be remembered that on injecting the Dog’s thyroid gland in 
a similar manner, the injection was seen emerging from the gland in lymphatic vessels, 
which ran to neighbouring lymphatic glands.) Examination of sections of the 
Pigeon’s gland, thus injected, shows that the injecting fluid has entered vessels con¬ 
taining red blood-corpuscles. The same vessels become filled on injecting in like 
manner with a solution of nitrate of silver. To ascertain whether by the puncture- 
method the blood-vessels really become injected, another gland was injected with 
Berlin blue from the lower part of the carotid artery, the artery at the same time being 
secured above the gland. In this case, in which the injection had entered the 
capillaries and veins, it was evident that these were the same system of vessels that 
had been injected by the method of puncture. It may therefore be stated that on 
repeated injections of the thyroid gland of the Pigeon, both with Berlin blue and with 
nitrate of silver, by the method of puncture, / have been unable to inject any system 
of lymphatic vessels, but have always found the injection in the blood-vessels of the gland. 
The blood-vessels of the thyroid gland of the Pigeon also present the following pecu- 
