628 J. T. PATTERSON 



phenomena have an interest lying along a different line. In 

 fact there is considerable evidence to indicate that polyovular 

 follicles and such multiple gestations are to be correlated as cause 

 and effect. This applies not only to cases of multiple pregnan- 

 cies among forms that are normally uniparous, but also occa- 

 sionally to cases in animals that are normally multiparous. Ac- 

 cording to Wilder ('04) von Franque ('98) was the first to start 

 the discussion which has led up to the conclusion that polyovu- 

 lar follicles bearing two eggs might result in the origin of twins 

 not compound monsters or duplicate twins, but to fraternal twins, 

 as Wilder points out, since the eggs must be fertilized by different 

 spermatozoa. 



The theory that polyovular follicles may account for 'fraterni- 

 ties' of this sort receives considerable support in the case of a dog 

 reported by Smyth ('08). In 1906 he obtained a young setter 

 pup from a litter of fourteen pups (four dogs and ten sluts) born 

 to a Gordon setter. When the pup was ten months old she was 

 spayed for reasons of convenience, and upon preparing the ovaries 

 in sections it was discovered that not a few of the ripe follicles 

 held double and triple ova. The ovaries from one of the other 

 pups were also sectioned, and they too possessed polyovular 

 follicles, one containing as high as seven ova. In 1907 one of 

 the sluts from this same litter gave birth to nine pups, three 

 dogs and six sluts. It is a great pity that the ovaries from this 

 bitch were not studied, as well as those from her mother. But, 

 even though the data are not as complete as might be desired, 

 still they point unmistakably to the fact that a tendency to poly- 

 ovular follicles was inherited in this family of dogs; and, further 

 more, they suggest that the unusually large litters of the mother 

 and her daughter might in part be accounted for on the basis of 

 compound follicles. 



It is a well-known fact that other normally multiparous animals 

 sometimes show a tendency to bring forth very large litters. 

 While it is of course possible that in such cases all of the ova 

 belonging to a given litter may come from simple follicles, yet 

 it is not improbable that some of them may come from polyovular 

 follicles. There is but one way in which it would be possible to 



