ERASMUS DARWIN, HERBERT, FREKE. IIg 
Descent. In 1795 he published, under the title of “ Zoono- 
mia,’ a scientific work in which he expresses views very 
similar to those of Goethe and Lamarck, without, however, 
then knowing anything about these two men. It is evident 
that the Theory of Descent at that time pervaded the intel- 
lectual atmosphere. Erasmus Darwin lays great stress upon 
the transformation of animal and vegetable species by their 
own vital action and by their becoming accustomed to 
changed conditions of existence, etc. Next, W. Herbert, in 
1822, expressed the opinion that species of animals and plants 
are nothing but varieties which have become permanent. 
In like manner Grant, in Edinburgh, in 1826, declared that 
new species proceed from existing species by continued 
transformation. In 1841 Freke maintained that all organic 
beings must be descended from a single primitive type. In 
1852 Herbert Spencer demonstrated. minutely, and in a very 
clear and philosophic manner, the necessity of the Doctrine 
of Filiation, and established it more firmly in his excellent 
“Essays,” which appeared in 1858, and in his “ Principles of 
Biology,” which was published at a later date. He has, at 
the same time, the great merit of having applied the theory 
of development to psychology, and of having shown that the 
emotional and intellectual faculties could only have been 
acquired by degrees and developed gradually. Lastly, we 
have to mention that in 1859 Huxley, the first of English 
zoologists, spoke of the Theory of Descent as the only 
hypothesis of creation reconcilable with scientific physiology. 
The same year produced the “Introduction to the Flora of 
Tasmania,” in which Hooker, the celebrated English 
botanist, adopts the Theory of Descent, supporting it with 
important observations of his own. 
