THE GENERAL CONSTITUTION OF LIVING BEINGS. 85 



to the heterotopy of some other element, that is, to the ap- 

 pearance of that element where it is not usually produced. 

 Cancer, for instance, that terrible cancer, gnawing and 

 spreading, is wholly composed who would have believed 

 it ? of an excessive development of epithelial cells iden- 

 tical with those of our skin, or differing from them only 

 by slight peculiarities whose origin is easily explained. 

 Phthisis, that terrible scourge which decimates our race, is 

 caused by the development of a matter called tuberculous, 

 composed of epithelial embryoplastic nuclei, become gran- 

 ular and fatty, and mixed with spindle-shaped bodies, all of 

 them elements that are formed in the system in the usual 

 state. The lungs are thus attacked and destroyed by prod- 

 ucts of a cheesy appearance, made by the effect of the 

 same law that governs normal products, but under different 

 conditions. Heterotopy discloses to us other phenomena 

 equally extraordinary. There have been found in the 

 ovary cysts containing in their inner wall a true skin, fur- 

 nished with papillae, epidermis, hairy follicles, hairs, and 

 perspiratory glands. Teeth have even been found devel- 

 oping in the abdomen. All these organs are accidentally 

 produced in those regions, having by fortuitous concourse 

 found the circumstances favorable to their appearance all 

 existing there. Robin has remarked, in the neighborhood 

 of certain glands of the body, the formation of small masses 

 consisting wholly of tissue identical with that of the 

 breast. So, too, late experiments by Oilier and Goujon, con- 

 firming those of Flourens, have taught us that bones may 

 be produced at any points in the system to which perios- 

 teum or fresh marrow is taken, in the stomach, for instance. 

 This singular production of bony substance has not yet 

 been observed taking place spontaneously, but it is easy to 

 effect it by experiment on animals. 



The formation of the tissue of a scar is nothing else 

 than a renovation of the layer-tissue of the skin ; and all 



