The Descent of Man

ky writes to me from Naples, that he has now
carried these observations yet further, and
should his results be well established, the whole
will form a discovery of the very greatest
value. Thus, if we may rely on embryology,
ever the safest guide in classification, it seems
that we have at last gained a clue to the source
whence the Vertebrata were derived. (25. But I
am bound to add that some competent judges
dispute this conclusion; for instance, M. Giard,
in a series of papers in the 'Archives de Zoologie
Experimentale,' for 1872. Nevertheless, this
naturalist remarks, p. 281, "L'organisation de la
larve ascidienne en dehors de toute hypothese
et de toute theorie, nous montre comment la
nature peut produire la disposition fondamentale
du type vertebre (l'existence d'une corde
dorsale) chez un invertebre par la seule condition
vitale de l'adaptation, et cette simple possibilite
du passage supprime l'abime entre les
deux sous-regnes, encore bien qu'en ignore par
ou le passage s'est fait en realite.") We should