Briggs mower with no choke?

[PeterS]

A charity I work for has a 2010 Toro Recycler with a 190cc Briggs. I got it running fine, but while cleaning the carb I noticed it doesn't have a choke.
How does this think get itself started with no choke? It works, but I don't understand why....
It looks like the one below. You can see at the top near of the carb an undrilled casting position for a choke. Does it somehow use the throttle to choke, or something?
I'm sure one of you knows. Thanks. P.

 

[Scrubcadet10]

That's a primer type carburetor, there should be a red primer bulb (sometimes black) on the front of the air filter base, when that is pushed, it pushes air into the carb bowl and fuel through the main jet, adding extra fuel to the intake for a richer, easier start up.

 

[Scrubcadet10]

the air filter base should look like this, thats the primer bulb on the front in red

 

[PeterS]

But don't lots of mowers have a primer and a choke, both? Or am I wrong?

 

[Scrubcadet10]

I've never seen one with both
, A choke keeps air out, so the fuel mix is richer, a primer adds fuel so the mix is richer,

 

[PeterS]

I've never seen one with both
, A choke keeps air out, so the fuel mix is richer, a primer adds fuel so the mix is richer,

I'm smarter today then. Thanks.