The size of the aorta in warm-blooded animals and its relationship to the body weight and to the surface area expressed in a formula

Abstract

In recent years it has become increasingly evident that many of the most important problems of physiology and of experimental pathology cannot be investigated in a satisfactory manner until accurate data have been made available regarding the quantitative differences which are exhibited by the organs, tissues, and fluids of the body in normal animals of different species and of varying weights. Results obtained with animals of any given weight cannot be applied, even within one and the same species, to yield con­clusions regarding animals of a different weight until it has been determined with precision how the various organs and tissues of the body are related to the size of the individual. Moreover, it will not be possible to compare one species with another, or to apply the results deduced from any given species to any other species of animal, until we can establish the existence of some kind of quantitative correlation between the measurements in different species. That this will prove to be possible seems likely from an examination of the results already obtained by us in studying the various factors which influence the circulatory system and determine the size of the heart (1). In connection with our study of the blood and cardio-vascular system under normal and pathological conditions, it was shown that the blood volume of normal animals of any given species is proportional to their body surface, and follows the formula B = W n / k , where k is a constant for the species and n is approximately 0.70-0.72 (2), (3). Accordingly it became of interest, in view of the theories which have been put forward regarding the volume of the blood and the size of the aorta in chlorotic conditions, to endeavour to determine how the size of the aorta is related to the weight of the individual in any given species of animal.