GESTATION. 149 



The question has been much discussed as to whether these multiple 

 births in animals ordinarily uniparous, are the result of one or successive 

 copulations. The majority of the authorities in such matters are certainly 

 of opinion that a single copulation will suffice to fecundate several ovules, 

 and they doubt if, after a fruitful copulation, it is possible for the sperma- 

 tozoa to reach the ovary, supposing a second ovule to be developed, unless 

 the second impregnation takes place very soon after the first, and before 

 the fertilized ovule had descended into the uterus. The well-authenti- 

 cated instances of superfoetation, though rare, nevertheless rather militate 

 against this opinion ; and it would appear to be impossible to explain why 

 one animal among several hundreds, perhaps thousands, should alone 

 bring forth " doubles " or " triplets," while all the others, placed in the 

 same hygienic conditions, have only one offspring. It is a fact, however, 

 that wdth certain breeds of Sheep an abundance of nourishment and plen- 

 tiful years dispose to these multiple births. 



What has been said of uniparous animals does not at all apply to those 

 which are multiparous ; for although the latter may be impregnated at a 

 single copulation, and bring forth several young, yet, as a rule, they are 

 fecundated more than once, and in fact do not cease to seek the male 

 until after several copulations. 



In these cases of multiple gestation in creatures naturally uniparous, 

 one of .the fcetuses occupies the ordinary situation of single gestation : the 

 head towards the cervix uteri, the larger portion of the trunk in the body 

 of the uterus, and the hind quarters and limbs in one of the cornua. The 

 second foetus occupies the whole of the other cornu ; with the head 

 turned back, or, as occurs not infrequently, in the opposite direction, and 

 so on. 



The duration of gestation in these cases is generally shorter than that 

 of single pregnancy in the same animal, probably in consequence of the 

 unusual distention, as well as derangement of the principal functions in 

 the mother. The weight of the young, individually, is usually less than 

 the average ; but, collectively, it may be very much greater than that of 

 one young creature produced at a birth. Thus in the quadruple birth re- 

 corded by Magdinier, each foetus weighed ten to eleven kilogrammes ; in 

 that by Bouchard they only weighed from eight to nine kilogrammes ; in 

 the quintuple birth described by Cassina, each calf weighed seventeen 

 kilogrammes, or eighty-five for the entire birth — an enormous weight. 

 Lignana, another Italian veterinary surgeon, mentions that in a double 

 birth in a Cow, one of the calves which was born dead, though at full 

 time, weighed twenty kilogrammes ; and the other calf, which was alive, 

 weighed forty-three. In the double birth observed at Saulsaie, in which 

 both calves were born alive, one was twenty-eight kilogrammes and the 

 other thirty -one. 



Free-martins. 



A curious fact in connection with this subject in the bovine species, is 

 that when the young are of both sexes, the female is in general unproduc- 

 tive. This fact is well known in many countries, where the female calf 

 receives a particular designation : as " Free-martin " in Britain ; in Hol- 

 land, " Queenen ; " in Germany, "Zwitter," or "Zwillingj" in Swabia, 

 " Zwicker ; " in Piedmont, " Mugn^ ;" in France, " Loures," " Taures," 

 etc. The old Roman agriculturists knew these animals as "Taurae." It 

 is very rare, indeed, that the male is infecund. Baumeister, however. 



