A Strange Abnormality in the Circulatory System of the Common Rabbit (Lepus Sylvaticus)

Abstract

IN the March number of the Naturalist an article appeared On the Frequency of Abnormalities in Connection with the Postcaval Vein and its Tributaries in the Domestic Cat (Felis domestica) Such variations are quite familiar to those who have charge of laboratory work in vertebrate anatomy. The abnormalities are, however, by no means confined to the region indicated in the above article. They are common to other parts of the circulatory system. Though the author does not discuss the probable causes of these abnormalities, he suggests that they may be due in part to domestication, in breeding, disease, drugs, and shock. I have found that abnormalities in the circulatory system are not confined to the domesticated cat, but are also of frequent occurrence in the common gray rabbit. The most noticeable variation that I have found, and the only one which I shall describe, was found in the venous system of the rabbit. I have found it but once and, as I have seen no mention of such an occurrence in the literature pertaining to this subject, I will describe it. In injecting the posterior vena cava from the heart I was amazed by the rapid filling of the portal veins. This continued until they were as well injected as the other veins of the body. The injecting fluid used was a starch mass which was too coarse to pass from the vena cava through the capillaries of the liver into the portal vein. The inference was that there was a vein of sufficient size forming a direct connection between the portal vein and the posterior vena cava. Careful dissection showed this supposition to be true. A small vein extended from the posterior mesenteric and united 639