300 The Porum

This problem of lay education in orthodontics is one which has been aeg- lected, and no doubt much good can be accomplished by further study of the problem.

W. R. H.

More About Identical Twins

In the November, 1934, issue of the INTERNATIONAL JOURNAL or ORTHo- DONTIA AND DENTISTRY FOR CHILDREN, there appeared in the Forum a communica- tion taking exception to the title of my article, “Cleft Palate Found in Only One of Identical Twins. ’ ’

The patient was treated by a St. Louis orthodontist for ten years and then because of a chance in his educational program was referred to me (in Phila- delphia). The preliminary history was furnished by those who had had him in charge. Because of the high professional standing of those who took the history, its authenticity was never questioned.

Unfortunately, it will be impossible for me to answer Dr. Waldo’s questions with regard to the physician’s examination of the placenta and the chorionic and amniotic membranes, because such proof has not been available. Because of the insistence of the attending physician that the twins, according to his examina- tion, were identical, even though modern scientific demands for such proof are unsatisfied, I have labored on the assumption which I incorporated in my re- port. Since all assumptions are debatable, it must remain so within the minds of those who will not accept it as such.

I have not tried to present an original claim, but because of the unusual interest embodied in this report I have allowed it to be published. At this writ- ing I should like to quote from Herbst and Apffclstaedt in their 1930 edition of Malformations of the Jaws and Teeth, pp. 131, 132.

“The significance of double formations in the pathogenesis of clefts of arrest lies in the following facts :

“ (a) Since a bilateral cleft of the lip and jaw may be present in both of twins, the cause is presumably either pure heredity, abnormality in the germ, or a fault in fertilization. At all events the cause must lie in the germ, for the twins are uniovular.

“ (b) Since clefts of the lip may occur on the right side in one twin and on the left in the other, the primary cause must be an inherited dis- position to cleavage, while the position of the cleft must be due to intrauterine influences.

“ (c) Since clefts of the lip and jaw may occur in one twin only while the face of the other is normal, heredity must be eliminated, and the defect can only have been acquired in utero. It follows from these facts that a great number of clefts of the jaw, depending only UpOn arrest, may occur without any hereditary influence, but that heredity, abnormality of the germ, and abnormal fertilization must be taken into account as causal factors.?’

1 wish to extend my thanks to Dr. Waldo for his interesting communication. Harry B. W&g?&.