VII. On the existence of four distinct hearts, having regular pulsations, connected with the lymphatic system, in certain amphibious animals

Abstract

I Had long observed that it was very easy to obtain lymph from frogs, because these animals have large lymph-spaces (Lymphräume) immediately under the skin, and between the muscles. If the skin of the thigh of a frog be cut, the lymph will flow pretty freely, and may be collected in a watchglass: it will continue fluid for ten minutes, and then coagulates; it is at first as clear as water. By this means, lymph can be exhibited to students, a matter of some importance, for medical men have very rarely an opportunity of seeing it, in the whole course of their lives; and the word has been very inappropriately applied to many heterogeneous things. Whether all the hollow spaces observed under the skin of the frog be true lymph-spaces, appears to me to be doubtful; several of them, however, most decidedly are so, especially those of the thigh. None of the other amphibia have so large lymph-spaces as the frog has, but they all appear to be provided with remarkable pulsating organs , which direct the motion of the lymph. These I first observed in the frog.