'26 OPINIONS AND DISCOVERIES 



for then they partake of both advantages. When hving 

 and unwashed they are black to look upon. The place 

 of attachment is neither at one point only, nor extending 

 to the whole sponge, for there are empty passages in the 

 space between, but a sort of skin is stretched round the 

 lower parts, and the attachment is at several points. Above 

 most of the passages are closed, but four or five are visi- 

 ble ; wherefore some persons say that these are the pas- 

 sages by which the sponge receives its food. 



" There is another sort which they call AplysicB, because 

 they cannot be washed clean. This last sort has the large 

 passages, but is otherwise quite close, and when cut through 

 they are closer and tougher than the sponge, and on the 

 whole like the substance of the lungs : and this sort is al- 

 lowed by all to have feeling and to be long-lived. They 

 are distinguishable in the sea from the sponges, in that 

 the sponges are white with the mud resting upon them, but 

 these are always black." 



So far it may appear that Aristotle is favourable to the 

 belief in the animality of the sponge, but vrhen we remark 

 the guarded manner in which he reports that opinion, and 

 recollect that the book which contains its evidence was in- 

 tended as a popular introduction to the more exact and 

 detailed treatises, " de Partibus," " de Generatione," &c. 

 we must look in the latter for the conclusions to which 

 his own observation had led him. Now in the work " on 

 the parts of animals," sensation is plainly denied to the 

 sponges, which, moreover, are asserted to have altogether 

 the character of a plant ; but, perhaps, we more correctly 

 reflect Aristotle's ^^ews when we represent the sponge as a 

 production intermediate between the vegetable and animal 



