Sentence:  It is not indeed impossible, that from the sperm of a cock, hen, or other animal, being once in putrescence, either from incubation or otherwise, some generation may ensue; not <WSD>univocal</WSD> and of the same species, but some imperfect or monstrous production ... 
Meaning of the word marked with <WSD> tags:  Having always the same drift or tenor; uniform; certain; regular.