DE. H. WATNEY ON THE MINUTE ANATOMY OF THE THYMUS. 
1067 
Oesterlin (37), 1843, first noticed that there are cells containing pigment in the 
thymus. 
Simon (2), 1845, wrote an elaborate essay, which obtained the Astley Cooper 
prize ; he dissected many rare animals, having access to the collection of the Royal 
College of Surgeons. He gave careful and accurate accounts of the position of the 
thymus in many Mammals, and described its position for the first time in Birds, 
Reptiles, and some Amphibia, incorrectly, however, in the Frog. Simon rejected the 
theory of Hewson (10), and considered that “the presence of the gland is co-extensive 
with pulmonary respiration; ” “ that it secretes into a closed cavity; ” that in most 
animals the secreted matter “ presents itself in a fluid form; ” in some animals in 
“ the solid form of fat; ” and that the gland “ fulfils its use as a sinking fund of 
nourishment in the service of respiration.” 
Barkow (21), 1846, in a monograph on hibernation, pointed out in his sixteenth 
chapter that it was known to Aristotle and to Martial, that hibernating animals 
are very fat. Barkow maintained the difference between the thymus and fat glands, 
and gave a very accurate description of the position of the latter. 
Goodsir (29), 1846, found no cavities or reservoirs in the substance of the thymus. 
He asserted that the thymus consists of lobes, grouped around germinal spots, which 
derive material for the formation of the cells from arteries passing through them. 
Robin (38), 1847, first noticed the thymus in the Fish. 
Handeield Jones (39), 1849-1852, noticed that the absorbent vessels of the 
thymus travel to glands in the anterior mediastinum. He found that the thymic 
corpuscles are not similar in appearance and structure to the colourless granular 
corpuscles of the blood. 
Hassall (40), 1849, said that the gland consists of a straight tube, with the follicles 
arranged around it in a spiral manner. He described the concentric corpuscles (which 
have sometimes been called the concentric corpuscles of Hassall) as parent cells, con¬ 
taining several granular nuclei, each of which is surrounded by one or more concentric 
lamellae. 
After this time nearly every writer dwelt on the structure of the concentric 
corpuscles, and their opinions on that subject do not differ so very materially from 
those of later writers ; but their views of the origin and functions of these bodies differ 
very widely. 
We may distinguish three opinions as to the origin of the concentric corpuscles. 
(1) That they arise from the cells of the thymus, (a) by endogenous formation, Hassall 
(40), Wedl (41), Gunsberg (42), Berlin (31): (b) as a retrograde process, Bruch (43): 
(c) in a similar manner to cancroids, Virchow (44), Verneiul (45), and His (46), 
1859 : (d) arising by a fatty metamorphosis of the thymic corpuscles, Echer (47) : 
(e) from the gland cells, with a super-imposition of amorphous substance, Kolliker 
(48), 1854, and Jendrassik (30): (f) from the gland cells, after passing through a 
stage of epithelial cells, Paulizky (49). (2) That they arise from the blood vessels, 
