DR. H. WATNEY ON THE MINUTE ANATOMY OF THE THYMHS. 
1105 
pink fluid. The lymph vessels, before being opened, were slightly washed with saline 
solution, which was carefully collected, to 'be afterwards tested ; then the lymphatic 
was cut, and the issuing lymph collected in a pipette. This method was employed, as 
the lymph-vessels are so small that it is impossible to introduce any capillary tube 
into them with certainty of success. The lymph of the large lymphatic of the neck, 
the blood of the thymic veins and of the jugular vein, were also collected. 
It was found that the lymph collected from the lymphatics of the thymus contained 
many colourless corpuscles of three varieties, of which the first is by far the most 
common. There are (l) small lymphoid cells, exactly resembling in every respect 
the small cells obtained by teasing the thymus (see Plate 92, fig. 71, The) ; they show 
very faint amoeboid movements, have a grey homogeneous aspect, and contain fine 
granules ; (2) spherical or oval cells of various sizes, containing granules, spherules, or 
masses of haemoglobin ; some of these haemoglobin masses exactly resembling coloured 
blood corpuscles (see Plate 92, fig. 71 C, D, E); (3) large cells with many radiating 
processes (see Plate 92, fig. 71 B). Some of these last cells contain haemoglobin 
granules, and others do not; they are more numerous than the second variety, but 
much fewer in number than the first. 
The lymph issuing from the thymus contained a very small proportion of coloured 
blood corpuscles, less than 1 per cent.; whereas that of the lymphatic of the neck 
contained a larger proportion. 
We therefore conclude that there are present in the lymph issuing from the thymus 
cells containing coloured blood corpuscles, and haemoglobin granules ; and that in the 
lymphatics of the thymus there are more colourless cells than in the lymphatics of the 
neck. Whether there are more colourless cells in the blood of the thymic veins, than 
in the blood of the jugular vein, could not be determined; in two cases out of six there 
seemed to be some increase in number, but in the other four, no ^increase could be 
detected. However, the blood of the thymic vein contained many masses of granular 
matter; the so-called Zimm,ermann’s corpuscles. 
Physiological Conclusions. 
In considering the uses of the colourless cells which issue from the thymus by the 
lymphatics, the first thought that presents itself is that these cells form colourless 
blood corpuscles. Two circumstances must, however, be borne in mind : the first, that 
though in Mammals there is no great, difference in size and appearance between some 
of the colourless blood corpuscles and the thymic cells (see Plate 92, figs. 71 and 76, 
ebe and The), there are considerable differences in Amphibia and Beptiles (see Plate 
92, figs. 73 and 74, ebe and The), still greater differences in the Bird (see Plate 92, 
fig. 75), and greatest of all in the Bay-fish (see Plate 92, fig. 72). The second 
circumstance is, that the fluid which passes along the lymphatics from the thymus 
does not, in Mammals, pass directly to the blood, but first into lymphatic glands or 
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