82 BRITISH SPONGES: 



In the native species of Tethea there are neither pores nor 

 oscula ; and Mr Edward Forbes informs me that in the living T. 

 Cranium he did not observe any currents of water passing into 

 or from the body. Audouin and Mihie-Edwards, however, have 

 seen these currents. When a Tethea, they tell us, is placed in 

 a basin filled with sea-water, and left for a considerable time 

 perfectly still, we then see distinctly all its oscula wide agape, 

 and we perceive also the ciu-rents which pass through them. 

 But if now the animal is irritated, or withdrawn for an instant 

 from the water, the currents slaken or are altogether arrested ; 

 and the oscula, contracting slowly and insensibly, become at 

 last almost close. — Hist. Nat. du Litt. de la France, i. p. 78. 



The propagation of the Tethea is by means of sporules or 

 gemmules generated within the sarcoid matter. The latter re- 

 semble the parent sponge in miniature, but they have no dis- 

 tinct rind nor nucleus, being composed of simple spicula woven 

 together by the albuminous matter. I can conceive no way of 

 escape for these from the body except by its dissolution, which, 

 we may also conjecture, with considerable probableness, is an 

 annual production. The naturalist who believes that sponges 

 have an affinity with the Fungi will see in these particulars a 

 correspondency which may strengthen his belief. The Tethea, 

 he may say, is the Sea's copy of the earth-born Sclerodei*ma ; 

 and he may remind us that, like the sporules of sponges, the 

 sponiles of Fungi are equally locomotive. The Chaos fungorum 

 of Linnajus is thus described : " Habitat, uti semen Lyco- 

 perdi, Agarici, Boleti, Mucoris reliquoinimque Fungorum, in 

 sua matre, usque dum dispergatur et in aqua exclusum vivit et 

 moritur, demum figitur et in fungos excrescit, observante illustr. 



0th. Mvmchhausen Lib. Bar. Zoophytorum metamorphosis 



e Vegetabili in Animale ; Fungorum itaque contrario ex Ani- 

 mali in Vegetabile." — Syst. p. 1326. 



