94 EEMAEKABLE SPIRAL FIBRES. 



directions, were developed. By careful examination, 

 however, at different periods of the development of 

 such a tissue, the observer will, in some cases, be able 

 to form as clear a conception concerning the manner 

 in which the interlacing fibres were deposited, as he 

 may gain of the mode of formation of a complex 

 spider's web, by careful examination at short intervals 

 during its formation, although he has not witnessed 

 the creature actually at work. So delicate are the 

 fibres in some tissues that they can only be detected 

 by resorting to artificial colouring; and careful in- 

 vestigation leads me to think that in many cases in 

 which a tissue appears perfectly homogeneous and 

 structureless, it is really composed of excessively fine 

 fibres, which cannot be clearly demonstrated by the 

 aid of the methods of investigation at our disposal. 



135. Movement of Bioplasm In all tissue-forma- 

 tion. The peculiar characters and arrangement of 

 some structures can be accounted for by the move- 

 ments of the bioplasm during their formation, and 

 conversely we may learn much concerning the move- 

 ments of bioplasm by a minute and careful investiga- 

 tion of the arrangements of the elementary tissue 

 which has been formed by it. In the formation of 

 the elastic cartilage of the epiglottis, for example, it 

 seems probable that each mass of bioplasm revolves 

 while it forms delicate fibres, which accumulate, and 

 at length appear to be arranged concentrically round 

 the space in which it lies. The fibres, in this case, 

 seem to be formed somewhat in the manner in which 

 the caterpillar spins its cocoon, except that in the 

 case of the tissue, the process is interrupted, while 

 the last is a continuous operation. The attachment 

 of the bioplasm to some of these fibres may be dis- 

 tinctly seen in the particular texture referred to. 



136. Remarkable spiral Fibres. In connection 

 with the ganglion cells of the sympathetic of the 

 frog, I have described a very remarkable spiral 



