254 Hypertrophy. 



Operative grafting of thyroid tissue in case of loss of this organ 

 (as in goitre and operation for the removal of goitre), which is 

 apt to cause serious and even fatal disease, may successfully com- 

 pensate for the loss and is therefore of value from a therapeutic 

 point of view.* 



Hypertrophy. G-igantism. 



By the term liypcrtrophy is meant the increase of the essential 

 tissue of a part of the body, leading to enlargement of that part. 



Literally the term reallj- means excess of nutrition {virep and Tp6(pos, 

 nutrition), and from ancient times it -.vas used to express increase in 

 volume of tissues and organs when it was supposed that this depended 

 upon an increase of the nutritive supply to the ::tructure involved. Theo- 

 retically and from the microscopic findings, two types of increase in 

 volume may be conceived of : hypertrophy, in which the cellular elements 

 are seen to be increased in size, and hyperplasia, where a numerical 

 increase in the cells is the b.'isir, for the increase in the c'imtnsions of 

 the organ. [These are often spoken of as simple hypertrophy and numeri- 

 cal hypertrophy.! 



Where the increase of tissue involves the functionating elements 

 of an organ or part, as the parenchyma of a gland or the muscle 

 cells, it is spoken of as true hypcrtropliy; where, however, it con- 

 sists in an increase of the supporting tissue or so-called interstitial 

 substance alone (connective tissue, fat) it is a false hypertrophy. 



True hypertrophies occur because of increased demands upon 

 the activities of an organ and because of its increased functional 

 effort. Such examples are termed ivork hypertrophies. This is most 

 frequently seen in muscles, a very common example being met in the 

 increase in the skeletal muscles in gymnasts and the arm muscles of 

 wood choppers and smiths. The increased cardiac force in those 

 conditions of life in man and animals requiring continuously special 

 power of the heart is an expression of an hypertrophy. The heart 

 possesses in a marked degree the power of accommodation to in- 

 creased demands upon its ability ; its muscular substance in case 

 of permanent increase of labor increases {accommodative hyper- 

 trophy) up to a certain degree, determined largely by the relation 

 to the body weight. According to tlie investigations of Bollinger 

 and Parrot all animals wdiich are required to exert much muscular 

 energy because of their mode of life possess a heart heavier in 

 proportion to the body weight than those animals which lead a 

 sluggish life, as the dog in comparison with the hog, the deer in 



* In man thyroid preparation.s may be administered by the mouth. 



