FIXED MESSMATES. 65 



bundle of spicules. The learned microscopist of Berlin 

 had even thought that he had found the proof of this 

 opinion in the presence of woollen threads which were 

 observed in a specimen which Mons. Barbosa du Bocage 

 had sent him from Lisbon. Woollen threads had indeed 

 adhered to the spicules of Hyalonema, but they came 

 from the fishermen, who, when they drew these sponges 

 from the water, placed them carefully in their bosoms 

 under their woollen jerseys. 



Dr. Gray, of the British Museum, considers the 

 sponge as a parasite of the Polythoa, and that the 

 bundle of spicules belongs, not to the sponge, but to 

 the polyp. The most learned naturalist on the subject 

 of sponges, Mr. Bowerbank, expresses a different opinion. 

 The sponge and its spicules, according to him, are but a 

 single body, and the polyps are only a part of it. The 

 supposed polyps would only form a cloacal system for 

 the use of the sponge colony. 



Valenciennes, guided no doubt by the observations 

 of Philippe Poteau, was the first to recognise the nature 

 of the sponge and its spicules, but it is to Max Schultze 

 that we must give the credit of distinguishing the true 

 character of this extraordinary marine production. He 

 has shown that the bundle is formed by the extraordi- 

 narily long spicules of the sponge, and that the polyp 

 establishes itself upon it, by forming a sheath around 

 the bundle. . 



The fact is no longer doubted by any one, that the 

 long spicules form part of the sponge, and that the 

 polyp establishes itself on a part of the colony. But 

 science rarely advances by a single stride, and Max 

 Schultze, -like his predecessors, mistook the top of the 



