95 



ance is presented of any surface for attachment. The remaining por- 

 tions 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 por- 

 tions 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 jVog °f & n hich i n 

 diameter, which are differently arranged in different specimens. In 

 those portions which have a flocculent surface and loose texture, the 

 filaments are seen to be coiled up and interwoven in a tangled mass, 

 which presents no appearance of any definite arrangement (fig. 6) : at 

 the edges of such portions the filaments are seen distinct and separate 

 from each other, and shooting free into the surrounding fluid ; but 

 the examination of the centre presents a confused appearance where 

 the fibres cross each other in all directions, and intermingled with 

 them are seen some irregular granules of the same colour as the mass. 

 When those portions however are examined which have a membra- 

 nous character, a very distinct and definite arrangement of the fibres is 

 perceived, which here cross each other nearly at right angles, and are 

 so interwoven as to form a layer of greater or less strength and thick- 

 ness, (fig. 5) ; and it is apparently entirely owing to this variety in 

 the mode of arrangement of the fibres, that the different appearances 

 in the several masses already described are produced : the tangled 

 and confused aggregation of fibres producing the villous masses, the 

 loose ends of the filaments constituting in fact the villosity, and the 

 regular crossing of the fibres giving rise to the smooth, shining mem- 

 branous expansion. 



To examine however the minute structure of these filaments, which 

 make up, in fact, the whole mass of these singular substances, with 

 the exception of the granules just noticed, and which are few in num- 

 ber, it is necessary to use a magnifying power of 500 or 600 linear, 

 and the appearances then observed will be best described by the aid 

 of a diagram, (see Plate xi. and the description). 



The filaments which have been just described, are so exceedingly 

 minute, and require such high powers for their examination, that it 

 must be a matter of some difficulty to determine their exact nature. 

 The confervoid type however is, I think, so very strikingly and obvi- 



