INTRODUCTION 
The question of the inheritance of acquired characters 
is one which, by its generality, by its importance for the 
theory of the origin of species, and by its close connec- 
tion with still more difficult questions concerning the 
essential nature of life lying in the border land between 
physical chemistry and biology, passes beyond the con- 
fines of pure biology, and enters the wider field of posi- 
tive philosophy in the sense of August Comte, that is of 
scientific philosophy, which concerns itself with the most 
general results of the various sciences and with their 
fundamental interrelations. Is it any wonder then that 
this much discussed but unsolved question excites the 
keenest interest in philosophers and even induces some of 
them though they are not specialists, to attempt to study 
it thoroughly utilizing the abundant and valuable mate- 
rial which biologists and naturalists can now supply? 
It is so with the author of the present study. 
Formerly when he had not yet formed any fixed and 
definite opinion upon this subject, he had been inclined in 
a few philosophical and sociological studies to prefer 
Weismann’s theory of the non-inheritance of acquired 
characters to the contrary theory of Lamarck. The rea- 
son for this inclination even though no logically tenable 
opinion had been formed, lay in the demonstrated inabil- 
ity of any of the biological theories which had then been 
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