26o Maine: agricuIvTurai. kxperime;nt station. 1912. 



ably expect light to be thrown by the analysis of such cases. 

 These problems may be briefly designated as follows : 



1. The physiological problem. 



2. The problem of sex determination. 



3. The problem of secondary sexual characters. 



4. Certain problems of inheritance. 



The mere fact of the occurrence of multiple pregnancies in 

 forms normally bearing but one young at a time presents a 

 deeply interesting problem in the physiology of reproduction. 

 It means that the reproductive mechanism is not functioning 

 in the normal or usual manner. But just where and what is 

 the change from normal? Is the occurrence of twins and trip- 

 lets due to a departure from the normal in the functioning of. 

 the ovary, or of the tubes and uterus? Or in a word what is 

 the physiological basis of the occurrence of multiple gestation? 

 It is, of course, an obserA^ation as old as history itself, that 

 in the great majority (if not all) mammals where one young at 

 a birth is the normal condition multiple gestations occasionally 

 occur. Even in man, nearly the slowest in rate of reproduc- 

 tion of all mammals, there are occasionally as many as 4, 5, or 

 6 young at a single birth." 



Yet in spite of the fact that the phenomenon of multiple 

 pregnancy is so well known, data are wanting as to the under- 

 lying physiological causes upon which such occurrences depend. 

 It is not to the point to contend that normally uniparous ani- 

 mals showing an occasional multiple gestation are descendants 

 (in the course of evolution) from forms normally multiparous, 

 and that the occurrence of multiple gestations now is an "an- 

 cestral reminiscence". This mav all be true but it tells us noth- 



^It is not necessary to cite tlie literature on this subject here in 

 extenso. I merely give, by way of illustration for those who may be 

 curious about the matter, a few references from recent literature. 



Wilkins, S. V., Birth of Quadruplets Jour. Amer. Med. Assoc. Vol. 

 49, p. 43, 1907. 



Berheim, A., Quintuplets. New York Med. Jour. Oct. 22, 1904, pp. 

 (of reprint) 1-6. 



Miknovski, Yu. I., [Quintuplets] J. akush i jensk. boHez., St. Peters- 

 burg. Vol. 22, pp. 79-85. 1908. 



Wickersheimer, E., Une observation inedite de grossesse sextuple. 

 Bull. soc. d'obst. de Paris. T. xii, p. 320, 1909. 



i 



