and the internal organs of the pelvic cavity were also doubled. 

 In a similar monster there was an additional leg without a mate; 

 in the groin region of the extra leg were discovered an additional 

 ovary and three elevations which undoubtedly were nipples. In 

 this connection Baer thought the common phenomenon of super- 

 numerary nipples in humans as being possibly inherited. He cited 

 a case, described by Rober, in which a woman who had additional 

 mammae on the right side of the thoracic cavity gave birth to 

 a daughter with an additional mammae on the thigh. These 

 additional mammae subsequently secreted so much milk that the 

 woman could nurse, in addition to her own children, three 

 additional babies for six years. 



Besides the cases mentioned of parasitic formations in human 

 beings, Baer described an analogous case in a live adult cow? 

 (Figure 34, C) . In the middle of its neck there was an appendage 

 resembling in form the scaled-down underdeveloped posterior parts 

 with two deformed legs and a tail. The immediate investigation 

 showed, however, that the additional legs were not posterior 

 but anterior, and the tail-shaped structure contained a rudiment 

 of skeletal parts of the branchial girdle. Baer investigated 

 in detail the nerves of the parasitic formation from the cervical 

 part of the spinal cord. 



This thorough teratological work of Baer's remained incomplete 

 information intended for the second part was never published. 

 Probably Baer intended to include at the end of the work some 

 theoretical consideration of the origin of double monsters. 

 However, that which did appear in his published work is enough 

 to suggest his point of view on this subject. As previously 

 observed, Baer decisively rejected the idea that double monsters 

 result from the union of formerly separated individuals. He 

 concluded that double monsters can be formed only from the 

 fission of the formerly single embryo. Baer supposed that the 

 separation would be more pronounced the earlier the fission took 

 place. The cases of "parasitic formation" Baer was inclined 

 to interpret, apparently, from this point of view. It must be 



7. Information about this case was obtained by Velyaminov from 

 the Caucasus, which Baer published earlier under the title, 

 "Bericht uber eine ausgewachsene Missgeburt," BULL. SCIENT., 

 ACAD. IMP. SCIENCES DE ST. PETERSB (1836), No. 1, 

 p. 128. 



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