1104 
DR. H. WATNEY ON THE MINUTE ANATOMY OF THE THYMUS. 
In what way this haemoglobin arises, seems uncertain; whether from a conversion of 
the protoplasm of the cells into haemoglobin, or from an extravasation of the colouring 
matter of the blood into the cysts. 
Haemoglobin is also found in cells. These cells are of three kinds : (1) spherical or 
oval cells of various sizes, in which the haemoglobin is met with (a) in the form of 
granules (see Plate 86, figs. 19 and 20, c, d) ; or ( b) in the form of spherules or masses, 
some of which exactly resemble the coloured blood corpuscles (see Plate 86, fig. 21). 
These masses of haemoglobin enclosed in cells are oval in the Bird, Hep tile, and Fish; 
but circular in all Mammals, except in the Camel (see Plate 86, fig. 21 ; and Plate 92, 
fig. 77, d). These cells will be referred to afterwards. (2) The branched cells of the 
reticulum contain haemoglobin, generally in fine granules, at times in large masses (see 
Plate 86, figs. 18, h , and 14). (3) Cells or masses of protoplasm attached to the 
concentric corpuscles' also often contain haemoglobin (see Plate 86, figs. 16, h.h, and 
15, h ), and the concentric corpuscles themselves often contain this substance (see 
Plate 86, fig. 17, h). 
The Lymphoid Cells of the Thymus, when examined in the fresh state. 
In teasing the thymus of any animal, either with or without the addition of saline 
solution, the first point which attracts attention is the great number of small cells, 
varying somewhat in size (see Plate 92, figs. 74 and 76, The). The smallest are 
nearly the same size as the coloured blood corpuscles if the animal be a Mammal, 
(compare Plate 92, fig. 76, he and The). These thymic cells are nearly spherical, and 
have a very low refractive power. They are seen in many cases to be composed of a 
nucleus and of a delicate zone of protoplasm; in the very smallest, no zone of 
protoplasm can be found. If they are treated with saline solution, they appear to 
contain from three to six dark granules, which look like nucleoli; but on using a high 
power, and focussing carefully, and making the cells roll over under the microscope, 
the protoplasm is seen to be irregularly heaped up, and the corpuscles have somewhat 
of the horse-chesnut shape (see Plate 92, fig. 70). 
Characters of the Lymph and Blood issuing from the Thymus. 
The lymph and blood, as they issue from the thymus, were obtained from Calves 
and Oxen of various ages, from fourteen weeks to thirty months. The animals, seven 
in number, were killed in the ordinary manner by the pole-axe. The tissues of the 
neck were then divided, down to the lower part of the cervical portion of the thymus; 
the largest of the veins issuing from the thymus were tied, including in the ligature 
some slight amount of additional tissue; and the animal was left for ten or fifteen 
minutes. By that time, in every case but one, the lymphatic vessel issuing by the 
side of the veins was easily perceptible, and was seen to be filled with a very pale- 
