Organ Weights of Normal Rabbits

In November, 1921, a systematic study of normal rabbits was undertaken as a part of a more general investigation dealing with the subject of the animal organism in relation to disease. The present paper on organ weights is based on results obtained from a study of 350 male rabbits killed and examined between January 1, 1922, and July 1, 1924. Methods of conducting the experiments are described and the results are summarized in the form of a table and a series of text-figures. The organs studied were the heart, liver, kidneys, spleen, thymus, testicles, brain, thyroid, parathyroids, suprarenals, hypophysis, pineal gland, and representative groups of lymph nodes. The results recorded include maximum, minimum, and average weights, the median, the mode, the standard deviation, the probable error, the coefficient of variation, and the percentage distribution of organs of different weights. No final conclusions are drawn but it is pointed out that the results obtained are comparable to those that have been reported from similar studies of organ weight in man. Attention is also directed to the tendency to the occurrence of wide variations in the weights of nearly all organs, and to an apparent difference in the degree of correlation that exists between organ weight and body weight in the case of certain organs. In this connection it is pointed out that within certain limits the weight of the brain, in particular, and of other organs to a lesser degree appears to be independent of body weight. The results recorded in this paper are regarded as representing approximate values which are affected by numerous conditions for which correction should be made. These conditions will be considered in subsequent papers.