UPON THE COLOUR OF THE RIVER SPONGE. 263 



atmnality ; among those in the minority, I will mention a 

 very able botanist and zoologist, Dr. George Johnston, who, 

 in his essay on British Zoophytes, published in the " Maga- 

 zine of Zoology and Botany," states his view of these pro- 

 ductions in the following words : — " I cannot go the length of 

 Ellis, in considering it proved that sponges belong to the 

 same class [Zoophytes) ; Ellis, we have seen, knew that no 

 polypes were to be found in sponges.". ..."Now, this fact, in 

 my opinion, determines the point, for if they are not the pro- 

 ductions of Polypes, the zoologist who retains them in his 

 province, must contend that they are individually animals, 

 an opinion to which I cannot assent, seeing that they have 

 710 animal structure, or individual organs, and exhibit no one 

 function usually supposed to be characteristic of that king- 

 dom. Like vegetables, they are permanently fixed ; like 

 vegetables, they are non-irritable ; their movements, like those 

 of vegetables, are extrinsical and involuntary ; like crypto- 

 gamous vegetables, or Alg(B, 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 to any animal whatever." (12) 

 This author, therefore, restores the sponges " to the Vegetable 

 kingdom, to which the earlier naturalists (13) believed they had 

 a rightful claim." (14) 



I will not here venture to give any express opinion^ whe- 

 ther the Spongilla be a vegetable or an animal production, 

 but will merely notify, that after many repeated and careful 

 observations I have hitherto entirely failed in perceiving any 

 individual and decided marks of its animality ; though, on 

 the contrary, the facts of the want and intensity oi ihe green 

 colour, (15) as in plants, being caused by the absence and pre- 

 sence of light, may afford strong evidence that might be very 

 fairly advanced more in favour of its being nearer allied to 

 the AlgcB or Fungi, and so belonging to the vegetable king- 

 dom. (16) Future observations will alone set at rest this du- 

 bious question in Natural History. 



I am, however, most desirous that those naturalists who 

 reside near the sea-coasts, would ascertain whether light 

 does not cause ^m/Zfl^r effects on the colours {17) of the differ- 

 ent marine sponges, which, indeed, seems to me extremely 

 probable from the following statement : — " Je ne peux rien 

 dire de certain," observes M. Lamouroux, " sur la couleur 

 {des eponges), qui parait tres fugace et tres-variee ; d'apres 

 les auteurs qui les ont observees vivantes, les nuances qu'elles 

 presentent seraien£ nombreuses et brillantes ;" (18) and thus 



