THEORIES OF LAMARCK AND DARWIN 379 
inheritance of the same. His theory is comprehensive, 
so much so that he includes mankind in his general con- 
clusions. 
Lamarck supposed that an animal having become 
adapted to its surroundings would remain relatively stable 
as to its structure. To the objection raised by Cuvier that 
animals from Egypt had not changed since the days when 
they were preserved as mummies, he replied that the climate 
of Egypt had remained constant for centuries, and therefore 
no change in its fauna was to be expected. 
Species.—Since the question of the fixity of species is the 
central one in theories of evolution, it will be worth while to 
quote Lamarck’s definition of species: ‘All those who have 
had much to do with the study of natural history know that 
naturalists at the present day are extremely embarrassed in 
defining what they mean by the word species. . . . We call 
Species every collection of individuals which are alike or 
almost so, and we remark that the regeneration of these 
individuals conserves the species and propagates it in con- 
tinuing successively to reproduce similar individuals.” He 
then goes on with a long discussion to show that large collec- 
tions of animals exhibit a great variation in species, and that 
they have no absolute stability, but “enjoy only a relative 
stability.” 
Herbert Spencer adopted and elaborated the theory of 
Lamarck. He freed it from some of its chief crudities, such 
as the idea of an innate tendency toward perfection. In 
many controversies Mr. Spencer defended the idea of the 
transmission of acquired characters. The ideas of Lamarck 
have, therefore, been transmitted to us largely in the Spence- 
rian mold and in the characteristic language of that great 
philosopher. There has been but little tendency to go to 
‘Lamarck’s original writings. Packard, whose biography of 
Lamarck appeared in 19c1, has made a thorough analysis 
