As the composition of lymph depends upon the source from which, and the conditions under which, it has been obtained, it is unnecessary to state the results of a chemical analysis. It suffices to say that lymph contains all the substances which are present in the plasma of blood, but not necessarily in the same total amount or in the same relative proportions. Speaking generally, leucocytes are present in about the same numbers as in blood—6,000 to 8,000 to the cubic centimetre; but leucocytes are everywhere present: in blood, in the lymph, in lymph-vessels, in the tissue-spaces. As they are not passively floating bodies like red blood-corpuscles, but active migratory organisms, they tend to accumulate in one situation and withdraw from another, in accordance with the opportunities which the different localities afford. They desert effused lymph, blisters, ascitic fluid, and the like. They are not found in the lymph in the pericardium. There are fewer in the lymph coming from the intestines after a meal than in the same lymph during the intervals between meals. Their departure from effused lymph might easily be explained. It is not so easy to account for their comparative absence from the lymph in the lacteals when it is heavily charged with fat and other products of digestion. Such leucocytes as are present at this time are loaded with fat granules which they have stolen from the chyle, as the lymph in the lacteals is usually termed. One would need to be very intimate with a leucocyte before one ventured to give reasons for all its movements. Lymph contains the same proteid substances as blood, and in the same relative proportions, but usually in smaller quantity.