CHAPTER X. 



ALLEGED OCCURRENCE OF SUPERFETATION. 



From time to time reports of alleged and apparent instances of human super- 

 fetation appear in current medical literature. Reports of similar instances in other 

 mammals occur also, although more rarely, in the nonmedical literature. As recent 

 instances of the former may be cited the cases reported by Logan (1917) and 

 Gustetter (1918). Of instances of the latter may be mentioned the cases of King 

 (1913), Sumner (1916), and Harmann (1917, 1918). The latter group of cases 

 were found in the rat, the mouse, the cat, and the cow, respectively. 



Without accepting the alleged or apparent cases in mammals with bicornuate 

 uteri as unequivocal, it is easy to see that, aside from ectopic implantations, the 

 conditions under which superfetation necessarily would have to occur in the human 

 uterus may be totally different from those that may obtain in bicornuate uteri. 

 Since the usual intermenstrual period in women is 28 days, it would also seem, 

 as often asserted, that the older of two fetuses in a case of human superfetation 

 certainty would occlude the uterine cavity rather effectively, and alone make fertil- 

 ization of any ovum, liberated at a subsequent ovulation, difficult. It would seem 

 to do this, entirely aside from the possible effect of the cervical mucous plug so 

 frequently referred to in the literature. 



These things are true especially in such instances as that of Gustetter, in which 

 the time interval between the ages of two fetuses is estimated to have been as great 

 as 65 days. Moreover, it would seem that the development of the first fetus and 

 that of the corpus luteum in such a case as this would have inhibited the occur- 

 rence of subsequent ovulations. An obstacle to the implantation might also be 

 found in the condition of the decidua, even if later ovulation actually occurred. 

 Since Loeb (1912) found that in the pregnant guinea-pig the endometrium can not 

 be stimulated to form a new decidua, it is evident that the fertilized ovum might 

 encounter insuperable difficulties if similar conditions obtain in the human being. 

 However, if a young blastocyst really can become implanted on the bare surface 

 of an ovary, or on the peritoneum even, then it may well be doubted whether a 

 new decidual reaction is essential for implantation of the ovum in the human being. 

 Furthermore, when implantation in the Graafian follicle occurs, there is no de- 

 cidual reaction, at least nothing comparable to what occurs in the uterus, although 

 the proliferating luteal cells may possibly act vicariously to some extent. How- 

 ever, there are other obstacles to superfetation, such as those mentioned above 

 and the possible occlusion of the uterine tubal orifices in consequence of hyper- 

 plasia of the uterine musculature and mucosa. 



Although it is being established that ovulation and menstruation apparently 

 are not contemporaneous phenomena, succeeding ovulations nevertheless prob- 

 ably are periodic and separated by a considerable interval of time from each 

 other. Such a conclusion seems to be fully warranted, although it is, of course, 

 well known that ovulation may occur without menstruation in normal nonpreg- 



243 



