Grrrrrr......
Now to muddy the waters further :-)
Antony van Leeuwehoek and his Little Animals, by Clifford Dobell, an older Dover book that can still be had. If anyone likes this guy it's a great read.
Leeuwenhoek looked at spermatozoa from frogs, fish, insects (flies) birds and humans. This approximately 1677. His discoveries caused a revolution in the thought of reproduction and he did speculate on how these sperms were involved. So far, I have not been able to find out exactly what he thought.