The vertebral column was duplicated at the level of the 

 second-third thoracic vertebrae; from here anteriorly it 

 extended in duplicate, and posteriorly; a single vertebra 

 extended. As a whole, the calf was somewhat deformed, the 

 thorax and back were humped, the posterior legs were deformed, 



On opening, one heart was found, three lungs and two 

 trachea, and the corresponding presence of two heads with a 

 change in the number and location of the blood vessels 

 (Figure 13). The latter are described in detail with Wolff's 

 usual accuracy. This description can be bypassed in order 

 to come to the main part of the given subject, the article 

 "On the Origin of Monsters." 



First of all, Wolff compared two points of view about 

 the origin of twin monsters. One considered the possibility 

 of accidental collision and union of previously separated 

 embryos. "The famous Haller and (Jacques Benigne) Winslow, 

 who are equally great persons," Wolff wrote, 



have turned the arguments against this hypothesis . . 

 They noticed in the monsters accuracy and regularity 

 of the structure, not less than in the normal, which 

 could not occur in case of accidental collision and 

 union, or in case of accidental transmutation. 

 This regularity is recognized in our monsters as 

 well as in many others . Why does the esophagus of 

 one calf join with the esophagus of another calf, 

 and not with any other part; why do they accrete 

 with each other? Why does the lung of one accrete 

 with the lung of another; why is the anonymous artery 

 in the same manner attached to the anonymous artery 

 or to the aorta of another and is accreted with it? 

 Why, in any of the monsters, does the esophagus not 

 accrete with the jugular vein, the lung with the 

 liver, the carotid artery with the hollow vein? 

 Could parts of one fetus instinctively find tl e 

 corresponding parts of another? (p. 550) 



93 



