300 Harris Hawthorne Wilder 



(stage VIII), and end with one that possesses a very broad face, has 

 the eyes far apart, and a broad nose between them (stage IX). 



Between these extremes we may find all perceptible gradations, but 

 for our purpose here but one will suffice, an average human face, with 

 eyes and nose of average proportions (stage VIII). 



But the series does not end here even, for just beyond the face with 

 the eyes far apart occurs a stage in which there is a slight doubling of 

 the nasal septum or of some other parts of the nose (stage X) ; then one 

 with two distinct nasal components and a minute palpebral opening be- 

 tween (stage XI). This median eye is in all points similar to that 

 of the type with which we began the series, save that here, if we should 

 analyze the case more completely, we would find that the components 

 of this median double eye would have their potential outer sides together, 

 while in the former case the relation of the eye components is that 

 of a normal pair of eyes, with the inner aspects together. These rela- 

 tions become apparent if we compare members of the series a little 

 more doubled, with the two components of the double eyes more com- 

 pletely developed. 



After this the stages that follow, not all of which are shown in the 

 diagram, repeat, in respect to this median double eye, the external 

 appearances shown in the first part of the series; there comes first 

 the doubling of the pupil, then that of the iris, and lastly that of the 

 entire eye-ball, although internally there is always the reverse relation- 

 ship of the muscles and nerves, as will be shown later on. After the 

 eye-ball is completely doubled there follow several stages in the gradual 

 separation of the ear components, and finally two complete heads upon 

 one neck, a typical Dicephalus. The relations of this form of monster 

 to other forms of diplopagi are too well known to necessitate repetition 

 here, but the reader may be referred to my former paper on the subject, 

 in which is shown a farther continuation of the Dicephalus series, and 

 the relation of this line to the various forms of Ischiopagi. 



That such a complete series may be made by the use of both normal 

 and abnormal types, while not in itself constituting a proof of any real 

 relationship between them, is still highly suggestive of a similar cause 

 at the basis of all, and that one which is fundamental, most probably 

 existing in the germ itself. The exact similarity of form, even to minute 

 anatomical details, between parts of the same degree of development on 

 either side of the normal, that is, in both "defective" and "excessive" 

 mon>ters (monstra in defectu et monsira in excessu of the older teratol- 



