18 LIVERPOOL BIOLOGICAL SOCIETY. 
conveyed, according to this theory of heredity; to the 
offspring. But we have already seen that there are some 
reasons for believing that such acquired characters are 
inherited. Whether, then, are we to relinquish a theory 
which is in accord with most of the facts of heredity and is 
supported by strong evidence, or are we to adopt this 
theory, and deny that acquired characters are inherited 
because our theory cannot explain such an inheritance. 
The former would be rash until we have a better theory to 
substitute: the latter would be unscientific. It is better 
to take neither course, but to adopt the germ-plasma 
theory as a provisional theory of heredity, with the 
addition that acquired characters may be inherited, though 
we are still ignorant of the process by which that is 
effected. 
In this question of the bearing of acquired characters 
upon the theory of heredity, we have, then, a most 
inportant point in the philosophy of Biology, in regard to 
which there is still some doubt and some difference of 
opinion amongst evolutionists, and it is a matter which 
should, if possible, be settled experimentally. Although a 
boundless field for work stretches out in every direction 
around the biologist, still what most seriously demands — 
our attention at present is, I believe, practical work, 
especially observations and experiments having a bearing 
upon evolutionary problems—work which will support 
and control our speculations, and which must be carried 
on, not in the study, but in the laboratory and the 
biological station, in the field and on the sea-shore. 
There have been during recent years, as we have seen, a 
number of remarkable essays upon the various parts of the 
theory of evolution—all of them replete with ideas sug- 
gestive of lines of research and subjects for observation 
and experiment; and the value of these speculations and 

