18 C. W. M. Poynter 
versus is the result of mechanical influences acting through 
the persistence of the right-sided umbilical and omphalomesen- 
teric veins. Dareste (1877) and Fol & Warynski (1881) have 
produced the condition experimentally, but have added little to 
our knowledge of its etiology. The orderly reversal of struc- 
tures in true situs transversus does not always occur, Lochte 
(1894) having collected thirteen cases in which only part of the 
viscera had rotated in the wrong direction. 
It has long been recognized that the heart may be transposed 
while the abdominal viscera and the lungs are normal. This con- 
dition is known as dextrocardia. A review of the literature 
shows that observers have no clear idea of this congenital condi- 
tion, for cases of pathologically displaced hearts are frequently 
reported under this head and clinical diagnoses are frequently 
made notwithstanding the fact that the condition is extremely 
rare. 
Both in cases of situs viscerum transversus and dextrocardia 
alone the heart and great vessels may show anomalies similar to, 
1. €., mirror pictures of, those encountered in individuals who are 
normal except for the defect in question. It follows that the 
anlage of the heart not only does not always follow the other 
structures either in situs solitus or situs transversus but that one 
loop may be normal and one or both of the other loops trans- 
posed. Lochte (1898) formulated the general conclusion, “ Jede 
korregierte Transposition bei situs solitus ist einfache Transposi- 
tion bei situs transversus.” 
The cases of situs viscerum transversus are too numerous to 
burden this report with their repetition, but I have included the 
following cases of dextrocardia for the benefit of those who may 
be interested in their more careful study. 
Eschenbach (1769), Abernethy (1793), Otto (1816) 2 cases, Breschet 
(1826) 2 cases, Meckel (1826), Otto (1829), Jasinski (1861), Falck (1877), 
Kriezer (1880), Pope (1882), Kundrat (1888), Grunmach (1890), Graan- 
boom (1891), Lochte (1894), Paltauf (1901), Nagel (1909), Geissler 
(1911). 
As has been shown, we cannot consider the anomalous position 
of the great vessels independently of the heart, and before we 
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