622 



THYMUS GLAND. 



Fig. 184.* 



open into a small "pouch""* which is situated at their base, and leads 



to the central cavity, the " reservoir of the thymus^ 



The Reservoir is lined in its in- 

 terior by a vascular mucous mem- 

 brane, which is raised into ridges 

 by a layer of ligamentous bands 

 situated beneath it. The liga- 

 mentous bands proceed in various 

 directions, and encircle the open 

 mouths (pores) of the secretory 

 cells and pouches. This ligament- 

 ous layer serves to keep the lo- 

 bules together, and prevent the 

 injurious distension of the cavity. 



When either gland is carefully 

 unravelled by removing the areolar 

 capsule and vessels, and dissecting 

 away the reticulated areolar tissue 

 which retains the lobules in con- 

 tact, the reservoir, from being folded 

 in a serpentine manner upon itself, 

 admits of being drawn out into a 

 lengthened tubular cord^f around 

 which the lobules are clustered in 

 a spiral manner, and resemble knots 

 upon a cord, or a string of beads. 



The reservoir, pouches, and cells, 

 contain a white fluid " like chyle," 

 or "like cream, but with a small 

 admixture of red globules." 



In an examination of the thymic 

 fluid which I lately made, with a 

 Powell microscope magnifying 600 

 times linear measure, I observed 

 that the corpuscles were very nu- 

 merous, smaller than the blood 

 particles, globular and oval in form, 

 irregular in outline, variable in 

 size, and provided with a small 

 central nucleus. 

 In the human foetus this fluid has been found by Sir Astley in too 



* The course and termination of the " absorbent ducts " of the thymus of 

 the calf; from one of Sir Astley Cooper's preparations. 1. The two internal 

 jugular veins. 2. The superior vena cava. 3. The thoracic duct, dividing 

 into two branches, which reunite previously to their termination in the root of 

 the left jugular vein. 4. The two thymic ducts; that on the left side opens 

 into the thoracic duct, and that on the right into the root of the right jugular 

 vein. 



t See the beautiful plates in Sir Astley Cooper's work. 



