HYPERTROPHY TUMORS. 443 



this production is in almost every instance the result of the demand lor in- 

 creased muscular exertion which is consequent upon some obstruction to the 

 usual function of the part. Thus an extraordinary hypertrophy of the mus- 

 cular coat of the urinary bladder is often seen as a consequence of obstruc- 

 tion to the exit of the urine, through the presence of a stone in the bladder 

 or of a stricture in the urethra; so again hypertrophy of the muscular coat 

 of the gall-bladder may take place as a consequence of obstruction of its 

 duct by a gallstone ; hypertrophy of the muscular coat of any part of the 

 alimentary canal may be induced by the existence of stricture lower down ; 

 and even hypertrophy of the heart is generally, if not always, attributable 

 to obstruction to the exit of the blood which it propels, resulting either 

 from stagnation of the pulmonary circulation by the deficient aeration con- 

 sequent upon disease of the lungs (in which case the hypertrophy is limited 

 to the right side of the heart), or from thickening or induration of the semi- 

 lunar valves, or from narrowing of the orifices of the aorta and pulmonary 

 artery. It is curious, moreover, to observe, that hypertrophy of muscles 

 frequently becomes a source of increased nutrition of the bones to which 

 they are attached ; this being manifested not merely in the augmented bulk 

 of the bones of limbs that are specially exercised, but also in the increased 

 prominence in the ridges and processes to which the muscles are attached. 

 This adaptiveness on the part of the formative activity of the osseous tissue, 

 is curiously manifested also in the relation of the skull to the brain ; for if 

 the bulk of the brain be not too rapidly augmented, the skull will enlarge 

 accordingly, and this (in some instances) not merely by the extension of its 

 normal bones, but by the intercalation of new osseous elements, the " ossa 

 wormiana ;" whilst, on the other hand, if there be a diminution in the bulk 

 of the brain, the cranium may adapt itself to this also, by a thickening on 

 its internal surface (or concentric hypertrophy), this change, rather than a 

 diminution in the entire substance of the skull, being more liable to take 

 place in cases in which the cranial sutures have already closed, and the 

 nutrition of the bone has become inactive. 



357. The production of Tumors must be considered as a manifestation of 

 an excess of formative activity in individual parts, and as constituting, 

 therefore, a species of Hypertrophy. For a tumor may be composed of the 

 tissues which are normal to the part ; as we see especially in the case of 

 those tumors of the uterus, which are made up of an excess of its ordinary 

 muscular and fibrous elements. But, as Mr. Paget has justly remarked, 

 "an essential difference lies in this: the uterus (often itself hypertrophied) 

 in its growth around the tumor maintains a normal type, though excited to 

 its growth, if we may so speak, by an abnormal stimulus; it exactly imi- 

 tates, in vascularity and muscular development, the pregnant uterus, and 

 may even acquire the like power; and at length, by contractions like those 

 of parturition, may expel the tumor spontaneously separated. But the 

 tumor imitates in its growth no natural shape or construction ; the longer it 

 continues, the greater is its deformity. Neither may we overlook the con- 

 trast in respect of purpose, or adaptation to the general welfare of the body, 

 which is as manifest in the increase of the uterus as it is improbable in that 

 of the tumor." 1 A gradation is established, however, between true Hyper- 

 trophies and Tumors, by those productions of glandular tissues, which are 

 made up of the proper substance of the gland with which they are con- 

 nected, as the mammary, the prostate, or the thyroid, and which (though 



1 See his Lectures on Surgical Pathology, vol. ii, p. 2; also Dr. Handfield Jones 

 in Brit, and For. Med.-Chir. Rev., vol. xiii, p. 330; and Dr. Bristowe in Trans, of 

 Patliol. Soc., vol. iv, p. 218. 



