The Psychological Consequences of Heredity. 309 



structureless and alike, and that the development of each germ 

 consists in acquiring the structure peculiar to its species. Some 

 of them, even, such as Menckel and Serres, discovered in the 

 temporary and transient forms of the embryogeny of man and the 

 other vertebrates the arrested and permanent forms of invertebrate 

 organisms. At least this much is certain, that at a certain point 

 of their development the embryos of all vertebrates, whether birds 

 or fishes, reptile or man, present only the most general and the 

 simplest features of the vertebrate type. Nothing could differ 

 more widely than this from the hypothesis of ' little statues ' fully 

 formed. 



In our opinion, if we look at the theories on the origin of our 

 cognitions, that is, the embryogeny of mind, in the light of these 

 two hypotheses as to the embryogeny of the body, the philosophic 

 question assumes a new aspect. 



The spiritualistic or rationalistic school holds, after its own 

 fashion, the pre-existence of germs. Whether, with Descartes, we 

 accept innate ideas, or, with Leibnitz, hold that arithmetic and 

 geometry exist in us virtually, and that there are graven on the 

 soul truths which it has never known, is to hold that the soul, so long 

 as it has existed, has possessed all its constituent elements. 

 Experience perfects and completes it, but gives to it very little 

 indeed, compared with what it receives. Just as, in the hypothesis 

 of the pre-existence of germs, the minute being is developed, but 

 does not undergo any change in its essential parts, or in the rela- 

 tions between them, merely attaining greater size, filling up gaps 

 and acquiring a few accessory organs ; so in the spiritualistic 

 hypothesis, experience merely causes us to adapt ourselves to the 

 fundamental forms and laws of the human soul, to those ideas and 

 judgments which constitute it, so to speak, and which are to the 

 mind what the cerebro-spinal axis is to the body. This analogy 

 will appear still more evident when we remember that Leibnitz 

 compares the human soul, previous to experience, to a statue out- 

 lined by the veinings in a rough block of marble. 



As for epigenesis, its counterpart in philosophy is not, we take 

 it, ordinary sensationalism, but a new system which we are about 

 to describe in the words of Spencer, Lewes, and Murphy, and 

 which lays much stress on heredity. 



