254 



BLADDER OF FROG. 



would be absurd to attribute to physical forces alone, the 

 formation of such an elaborate arrangement of mutually 

 adapted tissues, as that depicted in my drawing, which, 

 however, only gives a veiy imperfect and rough idea of the 

 actual structure itself. 



That the complex apparatus I have referred to, was 

 designed, and for a definite purpose, no one who studies the 

 details of the structure can doubt. That the ultimate 

 arrangement seen in the adult was prepared for, and, as it 

 were, foreseen at a very early period of development, even 

 before tissue of any kind was produced, is a conviction 

 which will force itself more strongly upon the understanding 

 the more minutely and thoroughly investigation is carried 

 out. The unprejudiced mind will undoubtedly provisionally 

 adopt such conclusions, and act upon them until the time 

 shall arrive when we shall be able to learn more concerning 

 the actual nature of these things. 



Bladder of Frog. The ultimate ramifications of the 

 nerve fibres, portions of capillary vessels, and a part of a 

 minute vein from the frog's bladder, are represented in 

 PI. XIII. The connective tissue and the unstriped mus>- 

 cular fibres are not given in the drawing, in order that the 

 arrangement of the nerve fibres might be represented as 

 clearly as possible. 



One dark-bordered nerve fibre (<r), is seen dividing into 

 two, one of which at d, divides into its peripheral ramifica- 

 tions, consisting of very fine compound fibres. The 

 arrangement was described by me many years ago in the 

 " Phil. Trans." for 1862. The fine fibres which I believe 

 invariably accompany the dark bordered fibre and coil 

 spirally round it are also given. See " Phil. Trans," for 



