HYPERTROPHY; TUMORS. 557 



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 imitates, in vascularity and muscular develop- 

 ment, 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 con- 

 struction ; the longer it continues, the greater is its deformity. Neither may 

 we overlook the contrast 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, be- 

 tween true Hypertrophies and Tumors, by those productions of glandular 

 tissue, which are made up of the proper substance of the gland with which they 

 are connected, as the mammary, the prostate, or the thyroid, and which (though 

 frequently encysted) are sometimes met with as outlying portions of the gland 

 itself. There is another class of objects to which Tumors come into close 

 relation, and which must be referred, like them, to a local excess of formative 

 activity ; these are the " supernumerary parts" which are not unfrequently de- 

 veloped during foetal life, as, for example, additional fingers and toes. It seems 

 absurd to refer these, formed as they are by simple outgrowth from the limbs to 

 which they are attached, to the " fusion of germs," which has been hypotheti- 

 cally invoked to explain more important excesses, as those of additional limbs, 

 double bodies, or double heads ; and yet from the lower to the higher form of 

 excess, the transition is so gradual that what is true of the former can scarcely 

 but be true of the latter ; so that even complete " double monsters" must be 

 regarded, not as having proceeded from two separate germs which have become 

 partially united in the course of their development, but from a single germ, which, 

 being possessed of an unusual formative capacity, has evolved itself into a 

 structure containing more than the usual number of parts, and comparable to 

 that which may be artificially produced by partial fission of the bodies of many 

 of the lower animals. a We can scarcely fail to recognize, in this whole series 

 of abnormal productions, the operation of a similar power. In the formation 

 of a supernumerary part, this has been sufficient, not merely to produce the 

 tissues, and to develop them according to a regular morphological type, but to 

 impart to the fabric thus generated a separate and even an independent existence ; 

 thus producing an additional finger or thumb on each hand, a double pair of 

 arms or legs, a double head or trunk, or even a complete double body. In the 

 hypertrophy of a regular or normal part, the new tissues are still developed ac- 

 cording to a regular morphological type ; but they have not the power of indi- 

 vidualizing themselves (so to speak), and are so incorporated with the normal 

 elements as to augment the size of the existing organ. In the formation of a 

 tumor, on the other hand, whilst its component tissues are themselves perfectly 

 formed, and have a marked power of independent growth, the mass composed 

 of them is altogether amorphous, its configuration being usually determined 

 rather by the physical conditions under which it is produced, than by any 

 peculiar tendencies of its own ; so that we recognize the action of the formative 

 power, undirected by that morphological nisus, which normally models (so to 

 speak) the growing tissues into the likeness of the organ to which they belong. 



1 "Lectures on Tumors," in " Medical Gazette," 1851, vol. xlvii. p. 925. 



2 See " Princ. of Phys., Gen. and Comp.," \\ 646, 709, Am. Ed. ; Prof. Vrolik in 

 "Cyclop, of Anat. and Phys.," art. "Teratology," vol. iv. p. 976; and Prof. Allen Thom- 

 son on "Double Monstrosity," in "Edinb. Monthly Journal," June and July, 1844. 



