MONSTROSITY, in anatomy. When an infant, or the young of any animal, comes into the world impressed with morbid changes, which occur only in fetal life, and of which it has never been observed that they have originated in the same way after birth, such an infant or young animal is said to be a monster or monstrosity. Monsters were formerly regarded as prodigies of nature; and in the dark ages their occurrence in the human species was usually ascribed to the intercourse of demons and witches. It is now perfectly understood that the formation of those apparently anomalous beings may be accounted for by the same laws as those which govern the formation of perfect indi viduals—the only difference being that these laws in the case of monstrosity are more or less arrested or otherwise perverted.
Amongst the principal causes of monstrosity may be mentioned: 1. Something deficient or abnormal in the generative matter of one or both parents, because, as has been shown in the article HEnEDITARINESS, malformations are frequently transmitted from parents to the children. Here the morbid change is impressed upon the fetus at the moment of impregnation. 2. Sonic morbid condition of the maternal organs or constitution may exercise a disturbing influence on development. 3. Diseases and abuormal states of the placenta, of time membranes of the ovum, and of the umbilical cord, may induce an arrest of development; for example, it may be easily understood how abnormal shortness of the cord may favor the origin of fissure of the abdomen; while a cord of disproportional length may coil round one of the extremities, and by constric tion may dwarf it, or even amputate it. 4. Morbid influences acting directly on the fetus, as mechanical injuries and diseases affecting it, arc the most frequent causes of malformations. From the experiments of several observers, it has been shown that by hens' eggs to various mechanical influences during incubation, tlic develop ment of the embryo may be interrupted, or modified in such a manner as to give rise to malformations; and many observations tend to prove that mechanical influences affect ing the womb (kicks, blows, or falls)in the early mouths of pregnancy, produce certain malformations, by causing an arrest of development. Moreover, the fact that certain malformations usually occur only in twin or triplet pregnancies, favors the view that certain monstrosities are due to pressure and confined space.
Of the various classifications of monstrosities, the following is perhaps the best: 1. Malformations in which certain parts of the normal body are entirely absent, or are too small. 2. Malformations produced by fusion or coalescence of organs. 3. Malfor mations in which parts naturally united, as in the mesial line of the body, are separated, and clefts or fissures occur. 4. Malformations in which natural openings are closed. 5. Malformations of excess, or in which certain parts have attained a disproportional size. 6. Malformations in which one or more parts have an abnormal position. 7. Mal formations of the generative organs.
The first class includes (1) completely shapeless malformations, in which the monster presents the appearance of a lump or mass, with no indication of definite organs; (2) malformations which consist of only a more or less rudimentary trunk, with no head or extremities; (3) trunkless monsters, in which the inferior parts of the body are want ing, and little more than it rudimentary head is present, which, instead of neck and trunk, is furnished with a pouch-like appendage, cont.tining rudimentary viscera and pieces of bone; (4) malformations in which the head, and sometimes a part of the upper part of the body, are wanting, cons.ituting acephalic monsters, which are by no means rare, the number of recorded cases in the human subject being over 100; (5) malforma tions in which the whole head is not absent, but some of its component parts are want ing—as, for example, the brain, some of the cranial bones, the nose, or the eyes; (6) cases in which the extremities are absent or imperfect to a greater or less degree—for example, they may be mere stumps, with the fingers and toes either absent or rudimentary, or the hands and feet may appear to exist independently of arms and legs, and to be inserted immediately into the trunk; (7) cases in which all the organs may be present, but some of them may be too small—thus, there may be general dwa rfishuess. or the head or limbs may be abnormally small. None of the monsters of this class, except those Included in the last two groups, are viable.