same continuous surface formed the future left ventral wall 

 of one, and the future right ventral wall of the other 

 partner .... If union had occurred during the first day 

 of incubation, then the ventral walls could not unite, since 

 they did not yet exist; hence they were isolated from the 

 blastoderm only in the second day" (p. 110). 



Later Baer described some cases of monsters in man. 

 First he described twins which were joined at the forehead. 

 In his opinion, this case was similar to the described in 

 1501 by Sebastian Minister. Baer cited an early description 

 and illustration of a human double monster, according to 

 data provided by Schmidt, published in the journal ISIS 

 in 1825. He followed with general descriptions and drawings 

 of "parasitic formations," as Burdach called them — i.e. 

 additional parts attached to completely developed individuals, 

 which were without an umbilicus and were nourished through 

 its vessels. Baer referred to a similar case which he had 

 observed in Konigsberg. The case involved a living baby 

 whose incomplete individual hands and legs were attached to 

 its chest but who lacked a head and a large part of the 

 trunk . 



Referring to analogous examples from other authors, Baer 

 mentioned a case been earlier studied by Zagorsky.6 He 

 noted that that famous Russian anatomists' s description, with 

 the exception of some details, was completely correct. In 

 this parasitic formation, as in other analogous specimens 

 from the Academy's collection, the supply of blood occurred 

 from arteria mammaria of the original individual. In addition 

 to these cases,' Baer saw examples of formations of additional 

 extremities, always, however, connected with the other 

 additional organs. This category, called "parasitic formations," 

 also included those cases where two additional legs are present 

 with an atrophied foetus, attached to»the pubic region and 

 situated in the normal legs (Figure 34, D) . The genital organs 



6. P. Zagorsky, "Foetus humani monstrosi, alii bene formato 

 foetui adnati descriptio," MEM. ACAD. SCIENCES ST. 

 PETERSB., VI s£r. Sc. math, et phys., v. 2, book 2 

 (1833) , pp. 187-194. 



458 



