EXCESS IN VOLUME OF THE FCETUS. 375 



larity and energy of the uterine contractions, and the favourable position 

 of the foetus. 



Causes. 



Several causes may be in operation to lead to excessive development 

 of the foetus — either wholly or partially. Among these we may cite the 

 following as the principal : 



Prolonged Gestation. — It has been shown that the fcctus may be 

 retained without injury for several wrecks beyond the period usually 

 allotted for its expulsion, and there can be little doubt that during this 

 interval its development is continued. This extra-development being 

 unprovided for in the dimensions of the genital passages of the mother, 

 leads of course to protracted or difficult parturition. 



There are instances recorded of the foetus of the Cow and Mare 

 weighing 117, 165, and 189 pounds. It may therefore be readily 

 understood that the greatly exaggerated volume which this weight 

 represents, must meet with much resistance in passing through a canal 

 that, in ordinary circumstances, gives exit to a foetus weighing from 

 56 to 80 pounds. 



lieduced Number of Fivtuses. — With multiparous animals, when the 

 number of foetuses is smaller than usual — as with the Bitch which has 

 only one or two, instead of five or six — the excess of nutriment they 

 receive often increases their bulk to an abnormal degree ; and as almost 

 every breeder of dogs knows, this frequently leads to serious results in 

 parturition. 



Disproportion in Size between the Male and Female. — There can bo 

 no doubt that a disproportion in size between the male and female, in 

 many instances, exerts a marked influence in this direction. More 

 especially is this the case in crossing with different breeds, or in attempt- 

 ing to breed from too young females. 



Delorme, quoted by Rainard (vol. i., p. 474), says that he has known 

 a certain number of Camargue Ewes die every year through non- 

 delivery, they having been put to Dishley Rams, which were much larger 

 than the native Sheep. 



The case of small Bitches crossed by large Dogs is familiar to all 

 dog-breeders. There appears, indeed, to be a natural tendency in some 

 small-sized Bitches to seek intercourse with Dogs much larger than 

 themselves, and this preference not infrequently leads to fatal conse- 

 quences in parturition. 



But in many instances dystokia is due to exaggerated development 

 of some particular region of the fa-tus, and more especially of the 

 head — a peculiarity derived from crossing, or breeding from a male 

 possessing this character. Indeed, some authorities deny that cross- 

 ing small female animals with males which are generally larger, is 

 likely to prove a source of difficult parturition, provided there is nothing 

 unusual in the proportion of any region of the latter. It is pointed out 

 that, in the human species, small women are very often married to very 

 large men, and yet their accouchements are more or less easy. It has 

 also been remarked that Melingie, in order to form the breed of Sheep 

 known in France as the Charmoise, coupled the small Bcrrichonne Sheep 

 with the great New Kent Earns ; and yet in two thousand births only 

 one was diffictdt. 



A German veterinary surgeon, Nathusius, mentioned by Rueff and 

 Baumeister, asserts that in the cross between the small Merino Sheep 



