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 
