SPONGES, 



31 



versialists who have contended for scientific dominion over 

 these bodies ; naturalists of the highest eminence have 

 been arrayed on each side. We 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 we 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 are, 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 alga?, 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. 



