246 STUDIES ON PATHOLOGIC OVA. 



conceptus, it is conceivable that a new implantation might occur in spite of the pres- 

 ence of a dead conceptus. This, however, would be a case of pseudo-superfetation 

 only, for if the term has any real significance it can only mean the superposition 

 of a second pregnancy upon one that is still living. 



Sumner quite rightly called attention to the fact that in the great majority 

 of cases of superfetation recorded in man, one or both fetuses were macerated 

 before born, and King concluded that "many cases that have been reported as 

 due to superfetation unquestionably are instances of superfecundation or of 

 blighted ova." Nevertheless, King regarded the case in a sheep reported by 

 Arrowsmith (1834) as probably genuine, and added that "although Christopher 

 found that ovulation might occur during pregnancy in the cat, superfetation is 

 not known to occur in this animal." However, Jepson, in 1883, reported such a 

 case, and Harman (1917) another. Neither report, however, would seem to bear 

 critical scrutiny, although both are quite as trustworthy as other reports of alleged 

 superfetation. In the case of Harman it would seem more probable that intra- 

 uterine death of one fetus with survival of the other was responsible for the miscon- 

 ception. It should be recalled that such instances are relatively common in the 

 rat, guinea-pig, rabbit, ferret, marmot, pig, and some other mammals. These 

 phenomena have been discussed by Strahl and Henneberg (1902), Henneberg 

 (1903), L. Fraenkel (1903), Koebner (1910), Huber (1915), Mall (1915), and 

 Meyer (1917 a ). 



As is evident from figure 149, in which the so-called younger superfetus, 

 reported by Harman in a cat, is contrasted with a normal cat fetus (fig. 210, plate 

 8, Chap. XIII) of approximately the same length, the latter has a totally 

 different form. The same thing is evident also, although to a lesser degree, on 

 comparing the illustration accompanying Harman's article with one from Kunz 

 (1916), shown in figure 150. Since the latter, the larger of two macerated ap- 

 parent superfetuses, in the report of Kunz, was deformed by retention, it may 

 have measured a little more or less probably more than 10 mm. at the time 

 of its death. However, even were it a trifle older than the fetus in figure 210, as 

 its form would seem to suggest, the difference is slight and may be ignored for 

 purposes of comparison. Kunz spoke of the larger fetus, shown in figure 150, as 

 entirely normal, which it apparently was, for the deviations from the normal 

 form (figure 210), which the illustration so clearly shows, undoubtedly are due 

 to post-mortem, ante-partum changes so common in human abortuses. Kunz's 

 conclusion that all three fetuses in his case in the cat resulted from ova which were 

 fertilized approximately at the same time heartily commends itself. Kunz further 

 concluded that these specimens furnish no evidence for the occurrence of super- 

 fetation, in spite of the fact that two smaller macerated distorted fetuses, which 

 were only 9 and 10 mm. long, accompanied a nearly full-term fetus. 



Harman (1918) also reported a case in the cow which, however, she regarded 

 merely as one of "probable superfetation." Unfortunately this report rests very 

 largely on the statement of a veterinarian, who made no further examination of 

 the specimen. Hence it would seem that we have no unequivocal evidence regard- 



