on the Animal or Vegetable Nature of Sponges. 421 



zoarian polypes (as was shown even by Brandt), and which beai* 

 no sponge-spicules, but only sea-sand, in their skin, as I proved 

 in 1860. The great difference between the Japanese Hy alone- 

 mata and the Portuguese ones is, that the Japanese axial bun- 

 dles are artificially twisted, and compelled to remain in this form 

 by means of thread and wire. Moreover the Japanese siliceous 

 filaments, having been torn from their natural connexion, are 

 sometimes put together again in a reversed position, and nearly 

 always the entire direction of the axial bundle in relation to the 

 sponge covering it at one end is reversed. The superior, na- 

 tural sponge, which produces the axis, has been stripped off and 

 thrown away, and a new foreign sponge has been allowed to 

 grow, or been fastened upon the thicker end. 



By these new Portuguese observations, therefore, the subject 

 is, in my opinion, settled, and the forms of Hyalonema can cer- 

 tainly no longer be described as anthozoarian polypes; whilst the 

 origin of their siliceous axial threads has also found a satis- 

 factory explanation ; but neither can they be regarded as sponges 

 furnished with a projecting siliceous tuft. Moreover there can 

 now be no doubt that the Phytolitharia, hitherto known almost 

 exclusively as microscopic corpuscles, will certainly by these ob- 

 servations be enriched with Spongolithes of from 1 to 2| feet 

 in length, which may be designated hereafter as Spongolithis 

 vaginata Hyalonematum when they occur isolated, without their 

 sponge, in the sea-bottom, or as fossils in rocks. 



The notion which has lately been often expressed, that there 

 are sponges with frequently long, protruding tufts of filaments 

 of a siliceous axis at their apex, appears now to be due to muti- 

 lation, often brought about naturally, in the same way as in the 

 cortical polypes with horny axes, which may not unfrequently 

 be raised fresh from the S3a with dead horny points from 

 which the living polype-bark has been stripped off, and even 

 with the basal portion of the stem destitute of bark. In the 

 same way the spongy coat of the apices of Hyaloncmata and of 

 their bases may sometimes be lost, even in the sea, whilst the 

 rest of the covering continues to vegetate ; for it is organically 

 inconceivable that naked siliceous threads without a cellular 

 envelope should grow out freely from within. 



As regards the question whether these sponges themselves are 

 animals or plants, and whether, little as they are comparable 

 with the true polypes of the Anthozoa, they might be named 

 ])olypidoms in a much simpler series of forms, as, indeed, is in- 

 dicated by my former representations from Bacillarian and even 

 Monadic stocks, 1 see no inducement at present to give up the 

 opinion, already repeatedly expressed by me, that the Sponges 

 cannot be described as animals. It is true that the most recent 



