SPONGES. 
31 
versialists who have contended for scientific dominion over 
these bodies ; naturalists of the highest eminence have 
been arrayed on each side. Wo shall content ourselves 
with giving the judgment of Dr Johnston, the learned 
historian of British Sponges, and one well worthy of 
being listened to with respect ; and wc quote him the 
rather because his decisions, while they tersely exhibit the 
real merits of the case, have so yielded to accumulated 
evidence as to shift from the side first advocated to the 
opposite. 
When the “ History of the British Zoophytes ” was 
published, the author omitted the Sponges, and gave the 
following summary of his reasons for so doing : — “ If they 
are not the productions of Polypes, the zoologist who retains 
them in his province must contend that they arc, indivi- 
dually, animals ; an opinion to which I cannot assent, 
seeing that they have no animal structure or individual 
organs, and exhibit no one function usually supposed to 
be characteristic of the animal kingdom. Like vegetables, 
they are permanently fixed ; like vegetables, they are non- 
irritable ; their movements, like those of vegetables, are 
extrinsical and involuntary ; their nutriment is elaborated 
in no appropriated digestive sac ; and, like cryptogamous 
vegetables, or algse, they usually grow and ramify in forms 
determined by local circumstances ; and if they present 
some peculiarities in the mode of the imbibition of their 
food and in their secretions, yet even in these they evince 
a nearer affinity to plants than any animal whatever. 
A few years later, however, the learned writer published 
his “ History of British Sponges,” in the introduction to 
Brit. Zooph., p. 29. 
