│per kilo of body weight Primates (5)│ 7.7 grams│ Carnivora (6)│ 7.6 grams│ Rodentia (2)│ 15. grams│ Hyracoidea (1)│ 7.5 grams│ Ungulata (9)│ 3.5 grams│ Edentata (1)│ 5.6 grams│ Marsupialia (7)│ 7.6 grams│ Monotremata (1)│ 11.2 grams│ │ │Average 7. Steganopodes (1)│ 9.1 grams│ Anseres (1)│ 3.9 grams│ Struthiones (3)│ 7. grams│ │ │Average 6.7 ────────────────┴───────────┴─────────── This to be sure is not a very exhaustive list but is the result of our routine observations and subject to all limitations of such work. Grossly diseased organs are naturally excluded. More avian weights are not available because of the difficulty of removing the organ from its bed, in a manner assuring us of completeness. I am inclined to view our mammalian records as fairly representative. Figures to be found in text- books of human and veterinary anatomy correspond to those given by the authors just quoted and in our own list. The values for rodents, hyraces, edentates and monotremes may be modified by more figures. There is however one point which does not appear in the list. Small animals have relatively larger kidneys than large animals. This is perhaps most strikingly illustrated among the ungulates which have the lowest value quoted. A small deer had a kidney-to-body index of 5.9 grams per kilo while a camel had only 2.8. Judging by the work of Magnan the avian kidney should be larger than the mammalian, a conclusion with which I am inclined to coincide, even though the weights cited do not bear this out. In so far as the function and chemistry of the kidney and its excretion are concerned this study can supply little. The general metabolism is known for most animals, it being dependent upon diet and gastrointestinal discharge of excrement. What lessons can be learned will be discussed by Dr. Corson-White in the section on diet. Our observations upon the ability of the kidney to excrete normal urine are limited to the examination of vesical contents at death or of the occasional specimen obtained in cages in the quarantine room. Renal disease was formerly considered of little or no importance in veterinary medicine or at least was studied only as a specific separate and occasional occurrence. Kitt[37] systematized the knowledge of the subject at the time he wrote but it remained for Hutyra and Marek in their text-book to emphasize its general importance and to clarify diagnostic measures. Breindl[38] pointed out that nephritis occurs more often in acute general diseases, notably the specific infections, than was customarily thought, thus placing the subject for the lower animal where it is in human medicine.