134 PLAIN FACTS FOR OLD AND YOUNG 



those of the female. Excessive development, shown in 

 a peculiar manner, produces both kinds of organs in 

 the same individuals in a state more or less complete. 



Such curious cases as the Carolina twins and Chang 

 and Eng were formerly supposed to be the result of 

 the union of two separate individuals. It is now be- 

 lieved that they are developed from a single ovum. It 

 has been observed that the primitive trace (described 

 in a previous section) sometimes undergoes partial 

 division longitudinally. If it splits a little at the an- 

 terior end, the individual will have a single body with 

 two heads. If a partial division occurs at each end, 

 the resulting being will possess two heads and two pairs 

 of legs joined to a single body. More complete division 

 produces a single trunk with two heads, two pairs of 

 arms and two pairs of legs, as in the case of the Caro- 

 lina twins. Still more complete division may result in 

 the formation of two perfect individuals almost entirely 

 independent of each other, physiologically, but united 

 by a narrow band, as in the remarkable Siamese twins, 

 Chang and Eng. 



Strange Freaks of Development.— In a curious 

 case reported not a great while ago, a partially devel- 

 oped infant was amputated from the cheek of a child 

 some time after birth. 



A few cases have been reported in which partially 

 developed human beings have been found in various 

 parts of the bodies of individuals, which were not pro- 

 duced by any reproductive process, as they have been 

 found in individuals of both sexes. These remarkable 

 cases are undoubtedly the result of the inclosure of one 

 embryo within another. 



The precise cause of these strange modifications of 

 development is as yet, in a great degree, a mystery. 



