THE PRINCIPLES OF BIOLOGY. 
161 
tlie nature of life. Thus, the average life of an oak is con¬ 
sidered to be somewhere about 300 years, and that of a man 
not one hundred. But this contradiction arises through an 
incorrect method of estimating the average life. In the case 
of an oak, for instance, we must take the average life over 
all the seeds, whether they afterwards grow up to oaks or not. 
Every seed is living at the time it leaves the oak; and to 
tell the average life we must take all the children of the 
tree, and not exclude those which die in infancy. And 
similarly with animals. If this were done, we may infer 
that the average life would be found to be longer the higher 
it is. 
A VISIT TO CEYLON.* 
At first sight one would perhaps expect to find a new work from 
the distinguished Evolutionist who has so ably extended the Darwinian 
theory in his “ Histories of Creation and the Evolution of Man ” to 
be an abstruse and somewhat technical treatise. Nothing of the kind. 
This is one of the most delightful and readable books on natural 
history and travel that has appeared in these days. Like our own 
lamented, versatile, and enthusiastic Charles Kingsley, who ever 
cherished a desire to behold the Tropics and “at last” was gratified, 
so Professor Ernst Haeckel from boyhood seems to have had a similar 
longing, which in its turn was fulfilled. He says:—“That every 
naturalist who has made it his life-task to study the forms of organic 
life on the earth should desire to see for himself all the marvels of 
tropical nature is self-evident; it must he one of his dearest wishes. 
For it is only between the Tropics, and under the stimulating influence 
of a brighter sun and greater heat that the animal and vegetable life 
on our globe reach that highest and most marvellous variety of form, 
compared to which the fauna and flora of our temperate zone appear 
hut a pale and feeble phantom.” 
As the learned Professor’s journey was for the benefit of science, 
one would have thought that his fellow countrymen, one and all, would 
have aided him, where opportunity presented, to the best of their 
ability. But, alas, in this he found, as too many have done before, that 
“ a prophet is never without honour save in his own country.” It appears 
that the Academy of Sciences at Berlin, the most important institution 
of its kind in Germany, has the income or “ travelling allowance” arising 
out of the Humboldt Fund at its disposal. At the suggestion of friends, 
and as he had achieved all his scientific excursions during a quarter of a 
century at his own cost, he applied to the Academy for a grant in aid of 
his expedition to Ceylon. But it seems that the leading spirits of the 
Academy are “the most vehement opponents of the doctrine of 
* A Visit to Ceylon : By Ernst Haeckel, Professor in the University of Jena 
Translated by Clara Bell. London : Kegan Paul, Trench, and Co., 1883. 
