REPORT OF THE SECRETARY. 27 



organ of subordinate importance in the animal economy, and of its 

 real office the anatomist is still ignorant. Its function is not indis- 

 pensable to the maintenance of life. 



The kidneys are excreting and not secreting organs; and the 

 amount and character of the excretions depend upon certain materials 

 in the blood. When the kidneys are excised, other membranes and 

 organs assume their office; and it is probable that in lower animals, 

 which are without this organ, its functions are performed by the 

 mucous membrane of the stomach and intestines. As far as the ob- 

 servations of the author extend, the kidneys are larger in carnivorous 

 than in other animals. The urine of fishes is difficult to be obtained, 

 the bladders are almost always empty. The amount of urine excreted 

 by a warm-blooded animal is from forty to several hundred times that 

 furnished by a cold-blooded animal. 



From this very brief exposition of the results obtained some idea 

 may be formed of the amount of labor bestowed on these investiga- 

 tions ; and whatever estimate may be formed of the speculations of 

 the. author, there can be but one opinion as to the value of the facts 

 which he presents. 



The next article accepted since the date of the last report, and 

 which has been printed and partially distributed, will form a part 

 of the 9th volume. It is by J. D. Runkle, and is entitled, "New 

 tables for determining the values of the co-efficients in the perturb- 

 ative function of planetary motions which depend upon the ratio of 

 the mean distances." The object of these tables is to facilitate the 

 calculation of the places of the planets, and other astronomical re- 

 searches. 



In determining the mutual action of any two planets in our solar 

 system, there are certain quantities, depending upon the ratio of the 

 mean distances of these bodies from the sun, which must first be com- 

 puted. The number of these quantities, and the labor necessary to 

 compute each one of them, makes this first step in the reduction of 

 the mutual action of the two planets to numbers, a serious work. But 

 when it is remembered that there are fifty planets already known, 

 and that others, especially among the asteroid group, are probably 

 still to be discovered, the desirableness of determining all these quan- 

 tities by some short and easy process cannot admit of question. The 

 tables just published by the Institution accomplish this desired end 

 with the greatest possible facility. Their use gives the same advan- 

 tage in the calculations to which they are applied that a table of 

 logarithms affords in arithmetical operations. The tedious labor of 



