266 APPENDIX. 



to be found in almost every water, but the appearance of which to the 

 naked eye is so totally dissimilar to that of the substances under con- 

 sideration, that no one could for a moment suppose, without the aid of the 

 microscope, that they were, in the slightest degree, allied to each other. 



" The several portions of this substance in my possession differ from 

 each other in some respects in reference to their external characters, 

 though in their composition all are alike. Some of the portions are in the 

 form of riband-shaped masses, of wh^ph the largest is six inches in length, 

 varying from half to three quarters of an inch in breadth, and is about a 

 line in thickness : there are five or six portions of similar breadth and 

 thickness, and varying from one to two inches in length. These portions 

 are highly elastic, and may be stretched to a considerable length, returning 

 again to their former shape with considerable resiliency. This elasticity, 

 however, is chiefly observed when the pieces are stretched in the longitu- 

 dinal direction, as they are capable of very little extension transversely. 

 The margin of some of these portions is irregular and flocculent, being 

 formed evidently of minute filaments, and resembling the villous surface of 

 a mucous membrane, and in the largest piece the whole surface has this 

 velvety appearance. Others of these portions present more distinct evi- 

 dences of a fibrous arrangement, and distinct traces of fibres, or, as they 

 will be presently shown to be, bundles of filaments, may be observed ex- 

 tending through the mass, both longitudinally and transversely, but the 

 surface or the margins still preserving a flocculent appearance. One or 

 two of these pieces, of which the border is nearly smooth, present very 

 much an appearance of having been cast in a flattened or contracted 

 portion of the small intestines ; one of these especially, which is only four 

 lines in width, looks like a portion of the intestine of some small animal, 

 with its mucous membrane turned externally and flattened, but, like the 

 other portions, it is not hollow, but riband-shaped. The remaining portions 

 differ from these only in presenting no trace of the flocculent surface or 

 margins, and in being more completely membranous. They might, in 

 fact, be easily mistaken for portions of animal membrane, and being of a 

 closer texture have much less elasticity than the former portions. The 

 thinnest of these portions, which at its edge is nearly diaphanous, is very 

 smooth and shining, having almost a tendinous lustre. To the naked eye 

 it appears to be made up of fibres, both longitudinal and transverse, but 

 the longitudinal prevail, and the mass more readily splits in that direction, 

 the splitting taking place with a clean margin, as if cut with a sharp in- 

 strument. This fragment bears no distant resemblance to a piece of dura 

 mater, covered by the arachnoid membrane ; both surfaces are equally 

 smooth, and no appearance is presented of any surface for attachment. 

 The remaining portions are thicker, measuring nearly a line in thickness, 

 and present a more distinct appearance of fibres crossing at right angles. 

 They may, in fact, be readily split into masses of fibres, which very closely 

 resemble, both in colour and texture, the middle or fibrous coat of the 

 arteries, but being softer and more elastic. The whole of these portions 

 are of a buff colour, and are here described as they appear when examined 

 under water. 



" When a small fragment of any of these masses is placed under the 

 microscope, with an amplifying power of from 50 to 100 linear, it is seen 

 to be made up of very delicate filaments, the y^tf f an mc ^ ^ n diameter, 



