THE FLUIDS OP THE BODY 55 



abdomen and in the thorax. Each lymphatic gland is invested 

 by a strong fibrous capsule. Its artery enters, and its vein 

 and efferent lymphatics leave, the concave side (the hilus) of 

 the gland. The lymphatic vessels which bring lymph to it 

 pierce the capsule on its convex side. It is divisible into two 

 parts : (1) The adenoid tissue which surrounds the artery and 

 its branches ; (2) the open network of " lymph- ways " which 

 invest this adenoid tissue. Leucocytes divide in the adenoid 

 tissue. The young lymphocytes drop out into the lymph- ways. 

 As a stream of lymph, brought by the afferent vessels, is always 

 flowing into the lymph-ways, and out by the efferent vessel or 

 vessels, the lymphocytes are carried with it towards the 

 thoracic duct. A lymphatic gland is therefore an organ for 

 adding leucocytes to lymph in the course of the lymph-stream. 

 It has, however, another and equally important function. 

 Leucocytes which have picked up germs or other foreign 

 matter pass on with the lymph to a lymphatic gland. After 

 entering its lymph-ways they leave the lymph-stream, squeeze 

 into the adenoid tissue of the gland, and there come to rest 

 with their burden. They remain in the gland until the foreign 

 matter is digested, or, if it be indigestible, until they undergo 

 dissolution, when the particles of soot or pigment are deposited 

 from their debris in a harmless state. When the skin is 

 tattooed, much of the Indian ink and other pigment remains 

 where it was inserted with the needle, but some of it is picked 

 up by leucocytes and carried to the nearest lymphatic gland. 



Lymphatic glands are barriers which stop the spread of 

 infection. They are the stations to which our police carry 

 captured germs. The skin of the heel is abraded. Germs 

 from the soil, or elsewhere, which have accumulated in a dirty 

 stocking owing to the warm moisture enclosed by an imper- 

 vious boot, the woollen covering of the foot is a peculiarly 

 healthy place for germs enter the opened lymph-spaces of 

 the subcutaneous tissues. Leucocytes hasten to the spot. 

 They seize the invaders with their pseudopodia, engulf them in 

 their body-substance, enter lymphatic vessels, and are rolled 

 away by the lymph-stream. The instinct which brings them 

 in ever-increasing numbers to the breach in the protecting 

 skin can be explained only in terms of force. From our own 

 conscious action to the causes which determine the movements 



