Extra pipe going into cylinder?

Hi, its been a while since i was on here lol, used to have a speedfight but now have a Honda Lead 100cc as it was cheap im confused about something though, on the bottom of the cylinder next to the exhaust port there is another port which a metal pipe comes up over the top of the engine then connects to a really fat hose, it goes into some sort of plastic box? Never seen anything like it before. Can anyone give me some info on this? Thanks

 

something to do with emmissions at a guess