GENERAL DISEASES. 



By Rush Shippen Huidekopbe, M. D., Vet. 



[Revised In 1903 l)y Leonard Pearson, B. S., V. M. D.] 



ANIMAL TISSUES. 



The nonprofessional reader may regard the animal tissues, which 

 are subject to inflammation, as excessively simple structures, as simi- 

 lar, simple, and fixed in their organization as the joists and boards 

 which frame a house, the bricks and iron coils of pipe which build a 

 furnace, or the stones and mortar which make the support of a great 

 railroad bridge. Yet while the principles of structure are thus sim- 

 ple, for the general understanding by the student who begins their 

 study the complete appreciation of the shades of variation, which 

 differentiate one tissue from another, which define a sound tendon or 

 a ligament from a fibrous band — ^the result of disease filling in an old 

 lesion and tying one organ with another — is as complicated as the 

 nicest jointing of Chinese woodwork, the building of a furnace for 

 the most difGicult chemical analysis, or the construction of a bridge 

 which will stand for ages and resist any force or weight. 



All tissues are composed of certain fundamental and similar ele- 

 ments which are governed by the same rules of life, though they may 

 appear at first glance to be widely different. These are (a) amor- 

 phous substances, (6) fibers, and (c) cells. 



(a) Amorphous substances may be in liquid form, as in the fluid 

 of the blood, which holds a vast amount of salts and nutritive matter 

 in solution ; or they may be in a semiliquid condition, as the plasma 

 which infiltrates the loose meshes of connective tissue and lubricates 

 the surface of some membranes ; or they may be in the form of a glue 

 or cement, fastening one structure to another, as a tendon or muscle 

 end to a bone ; or, again, they hold similar elements firmly together, 

 as in bone, where they form a stiff matrix which becomes impreg- 

 nated with lime salts. Amorphous substances, again, form the pro- 

 toplasm or nutritive element of cells or the elements of life. 



(&) Fibers are formed of elements of organic matter which- have 

 only a passive function. They can be assimilated to little strings, or 

 cords, tangled one with another like a mass of waste yarn, woven 

 regularly like a cloth, or bound together like a rope. They are of two 

 kinds — ^white connective tissue fibers, only slightly extensible, pliable, 

 and very strong, and yellow elastic fibers, elastic, curly, ramified, and 

 very dense. These fibers once created require the constant presence 

 of fluids around them in order to retain their functional condition, as 



482 



