52 PROFESSOR HUXLEY. 
into their interior by the water circulating about or through 
them. If so, they would be animals to some extent capable 
of plant-like growth, and would thus be the reverse of those 
plants which have lately attracted so much attention on 
account of their being able to partially support themselves 
by means of complex animal food, which they can digest and 
absorb like the most perfect classes of animals. 
On the CuassiFicaTion of the AN1IMAL Kinepom.' By 
Professor Huxtey, Sec. R.S. 
Linn us defines the object of classification as follows :— 
‘‘ Methodus, anima scientie, indigitat, primo intuitu, quod- 
cunque corpus naturale, ut hoc corpus dicat pro-prium suum 
nomen, et hoc nomen quecumque de nominato corpore 
beneficio seculi innotuere, ut sic in summa confusione rerum 
apparenti, summus conspiciatur Nature ordo.” (Systema 
Nature, ed. 12, p. 13.) 
With the same general conception of classificatory method 
as Linneus, Cuvier saw the importance of an exhaustive 
analysis of the adult structure of animals, and his classifica- 
tion is an attempt to enunciate the facts of structure thus 
determined, in a series of propositions, of which the most 
general constitute the definitions of the largest, and the most 
special, the definitions of the smallest, groups. 
Von Baer showed that our knowledge of animal structure 
is imperfect unless we know the developmental stages through 
which that structure has passed; and since the publication 
of his ‘ Entwickelungs-Geschichte der Thiere,’ no philo- 
sophical naturalist has neglected embryological facts in form- 
ing a classification. 
Darwin, by laying a novel and solid foundation for the 
theory of Evolution, introduced a new element into 
Taxonomy. If a species, like an individual, is the product 
of a process of development, its mode of evolution must be 
taken into account in determining its likeness or unlikeness 
to other species ; and thus “ phylogeny ” becomes not less 
important than embryogeny to the taxonomist. But while 
the logical value of phylogeny must be fully admitted, 
it is to be recollected that, in the present state of science, 
1 Read at the Linnean Society, Dec. 4, 1874. Reprinted from ‘ Nature’ 
with the permission of the author. 
