252 



SKIN OF FROG. 



In the organs of man and the higher animals, we often 

 find several very different tissues in close relation to one 

 another. These have been developed at or near the same 

 time. They have grown simultaneously, though in some 

 cases at a different rate. Perhaps they are in very close 

 proximity, although they do not actually blend together or 

 become incorporated with one another. They perform very 

 different offices, although they may act in concert and 

 support one another. uch tissues may differ much in 

 structure and chemical composition, although they draw 

 nutrient supply "from the same source. All are subject to 

 decay and are liable to impairment of function, but they 

 suffer from derangement in different degrees, and will be 

 very differently affected by morbid processes. 



The general reader may form some idea of the wonder- 

 ful structure, arrangement, and combination of different 

 textures and their adaptation to one another so as to con- 

 stitute an active, growing, work-performing apparatus of 

 marvellous perfection, if he studies carefully the illustrations 

 which I have given in the following pages. 



With the aid of the brief description appended to the 

 figures in Pis. XII, XIII, XIV, and XV, the reader will, 

 I hope, be able to form some estimate of the great import- 

 ance of minute investigation as applied to the elucidation 

 of very delicate and complex structures, and will, I think, 

 be led to agree with me in the opinion that it is only by 

 prosecuting anatomical A inquiries in the most careful 

 manner, that we can hope to ascertain how many of the 

 most important tissues of the body really act during life. 



Vessels, Nerves, and Pigment Cells. Skin of Frog. In 

 PI. XII, I have figured some of the most important of the 



