Assertion: swan's death | /r/HasProperty | frequent cause of sterility
Facets:
value: in first crosses
type: LOCATION
value: from observations
type: OTHER
value: very
type: DEGREE
Source sentences:
text: "...from observations communicated to me by Mr. Hewitt, who has had great experience in hybridising pheasants and fowls, that the early death of the embryo is a very frequent cause of sterility in first crosses.