300 DR. MAX SCHMIDT ON THE DURATION OF [Apr. 20, 



its twenty-first anniversary. In this Journal I have recorded my 

 ohservations, and not only those referring to the living animal, but 

 at the same time those respecting the symptoms of disease previous 

 to death, and the anatomical results of the autopsy. 



On the keeping of birds there exists a comparatively rich literature ; 

 and special periodicals treat of this matter. 



Now it would be of great use if the age the different animals are 

 able to arrive at could be ascertained ; and in order to contribute my 

 share of experience, I added my own knowledge to the few notices I 

 could find in literature, and published them two years ago. 



I note with satisfaction that my example has been followed by 

 the Zoological Garden of Hamburg. 



For further completing these statistics I have drawn up the following 

 two summaries. The first contains the duration of hfe of the dif- 

 ferent animals in our garden, as far as it could be ascertained, while 

 the second expresses the average amount of life-time of the indi- 

 vidual specimens of the different classes of Mammals and Birds. 



In reference to the first, I have to add that the record has been 

 continued up to the 31st of December, 1879, and states how long 

 the still living animals have been in our garden. It is evident that 

 the numbers denote the real age only of those animals that were born 

 there, while to that of the others the time they have lived before 

 coming to our hands must be added. This difference cannot be 

 estimated as very great, as the animals are generally acquired in 

 their youth. 



Of course it is impossible to point out the age of every single 

 specimen we have ever possessed, but only such numbers have been 

 chosen as are sufficient to show distinctly how long such an animal 

 is at all able to live. No notice has been taken of exceedingly short 

 periods of existences, as it must be presumed that adverse circum- 

 stances were the cause of them. Wherever it was feasible the time 

 of life has been given strictly to a day. In other cases only the 

 number of years is recorded ; and there can be, at the utmost, a 

 difference of but a few months, more or less. 



Out of a greater number of statements concerning the same class, 

 only those have been selected that show the principal variations of 

 length of life. The numbers relating to animals that were still 

 living on the 31st of December 1879 are marked with asterisks (*). 



The time of observation has not in all cases proved long enough for 

 definite statements — some of the animals having been in our keeping 

 only for a short time, while others that have lived in our Garden 

 from its beginning are still enjoying life and health, and promise 

 to live on for some time longer. 



