Congenital abnormal diminutiveness affects the entire body, as dwarf stature (microsomia), the individuals being termed dwarfs, or pigmies. These are either born diminutive, or, owing to inherent predisposition, not developed after birth to the ordinary stature. Dwarf-growth manifests itself either in the corporal development remaining stationary at the stage of childhood, the not unpleasing outlines and proportions of which it then retains, or else it is founded in an arrest in the growth of the bones, especially those of the lower extremities, with simultaneous malformation of the osseous trunk. It is marked by a disproportion in the more important parts of the body - largeness and hydrocephalic shape of the skull; length of trunk coupled with shortness of extremities, especially of the inferior ones; deformity of bones, consisting in thickness, especially of the articular terminations. This latter dwarf-formation is always congenital, and the bone affection upon which it depends has been designated as congenital rhachitis; against which, however, we have as yet to urge that, however much its features resemble those of the rickets of childhood, the direct evidence of its identity with the latter is wanting.

Accordingly, dwarf-growths may depend, either upon a primitive vice of plasticity, or in an anomaly of development affecting specifically the osseous system. Growth may, moreover, become checked at an earlier or later period, subsequent to birth, by constitutional maladies of an exhausting kind, both congenital and acquired, and especially by such as affect the brain or spinal medulla.

Partial diminutiveness affects individual organs, systems, or sections of the body. It is founded sometimes in a primitive anomaly of, or in defective plasticity in, the germ; in pressure and in restriction of space within the uterus; or, again, in a hindrance to growth after birth, resulting from exhausting diseases, from paralysis; lastly, in atrophy. Where larger sections of the body are affected, such disproportions result as are observed in giant-growth, in dwarf-growth, and in numerous descriptions of monstrosity. Although it may affect every organ and system, it is nevertheless most conspicuous in the following: namely, the brain (and skull) [microcephalia]; the eyes [microphthalmus], the inferior maxilla [brachygnathus], the lungs (and thorax), the stomach and intestinal canal, the common integuments (shortness), the muscles, the skeleton, the heart and vascular system (especially the aortal), the generative apparatus.

It is necessary to observe, that -

(a.) In monstrosities, accessory, supernumerary parts are very frequently diminutive.

(b.) Formations checked in the development of their mass and volume, often exhibit an arrest in the development of their texture; for example, bones, muscles.

(c.) Preternaturally diminutive organs often display some other kind of deformity, referable to the same causal relations.

(d.) Next to diminutiveness is total absence, which, in reality, often applies to individual formations entering into the composition of a complex part or system.

In hollow organs preternatural diminutiveness manifests itself as coarctation, and even as complete imperviousness, which, when affecting the external orifice of canals, is termed imperforatio, atresia.

As contrasting with hypertrophy, atrophy here demands a special consideration.