and Observations on the component Parts of Membrane. 353 



became (like the Gorgonice) more or less transparent, and were 

 considerably softened. In this state, if they were touched with 

 ammoniac, the part thus touched became of a deep orange 

 colour, inclining to a brownish red ; and, when much softened 

 by the acid, ( if afterwards immersed in ammoniac,) they were 

 completely dissolved, and formed a deep orange-coloured 

 solution.* 



When digested with boiling distilled water, the Sponges 

 afforded a portion of animal jelly or gelatin, which was precipt- 

 tated by infusion of oak bark. 



The fine and more flexible Sponges yielded gelatin in greater 

 abundance, and more easily, than those which were coarse and 

 rigid. The gelatin was gradually and progressively imparted 

 to the water, and seems (even in the same Sponge) to be a 

 constituent principle, of different degrees of solubility ; and it 

 must be noticed, that in proportion as the Sponges (particularly 

 those which were soft and flexible) were deprived of this sub- 

 stance, in the like proportion they became less flexible and more 

 rigid, so that the remaining part, when dry, crumbled between 

 the fingers ; or, when moist, was torn easily, like wetted paper. 



As the above properties prove that Sponges only differ from the 

 horny stems of the Gorgonice, and from the Antipathes, by being 

 of a finer and more closely woven texture,-f so this similarity 

 will be corroborated by the following remarks. 



When exposed to heat, they yielded the same products, the 



* The same effects were observed when the horny stems of the Gorgonice, AntU 

 patbes, ES?c. (which had been long steeped in dilute nitric acid,) were immersed in 

 pure or caustic ammoniac. 



f This is particularly to be observed by comparing the coarse sponges (such 

 as Spongia cancellata) with the finely reticulated parts of certain Gorgonia, especially 

 those of Gorgonia Flabellum, when divested of the external membrane. 



ZZ 3 



