Longevity, 
[November, 
736 
teeth ; the period of gestation ; the development of the 
skeleton into the perfection of a bony fabric, with particular 
reference to the combination of the epiphyses or loose ends 
of the bones to the shafts of the bones ; and lastly, the 
pathological or diseased condition of the dead animal of the 
species that had arrived at its full longevity, in order to de- 
termine whether or not there was evidence of cause of death 
from disease of some particular organ, or whether there was 
no such evidence, but simply a history of general decay 
from old age pure and simple. 
“ We were told that in a hippopotamus which had recently 
died, and which was known to have just turned thirty years 
of age, the two sets of teeth had fulfilled their allotted duty ; 
that the bones of the skeleton were duly consolidated ; and 
that the organs of the body were equally degenerated ; so 
that death had occurred not from failure of any particular 
organ, but from failure of the organic parts altogether. In 
a sentence, the animal had died a natural death, and the 
constant of the term of life of it and its family was set 
down at thirty years, a constant to which all the fadts that 
could be collated in respedt to this species of animal defi- 
nitely pointed. 
“ From this line of fadts in respedt to one type of animal 
life we were led to others, and the rule laid down by the 
distinguished Flourens — by which the determination of 
natural old age is calculated on the basis of perfected ma- 
turity — was brought under review. The skeleton is perfedted 
when the epiphyses or loose terminal parts of long bones 
are firmly united with the shaft of the bone. When the 
date of such perfection of development is known in the 
mammalian class of animals, the simple process of multi- 
plying the age at that date by five gives the natural anato- 
mical life of the animal. The elephant came before us as 
an example. A young elephant, whose history has been 
related in the “ Philosophical Transactions,” died at the 
age of thirty years. At that age the epiphyses of its bones 
were not completely united with the shafts. It was nearly, 
but not quite, matured. Multiply thirty by five, and one 
hundred and fifty years stand as the natural estimate of the 
life of the elephant ; so that really an elephant might exist 
which had itself carried all the Governors-General of our 
Indian Empire. Moving from this animal of long life, we 
turned to the camel, to find full maturity at eight years, full 
life at forty. We turned to the horse, to find full maturity 
at five years, full life at twenty-five. We turned to the lion 
and the ox, to find full maturity at four years, full life at 
