the little black thing is the capacitor (condenser in easy language) its used to cancel out noise in the ignition circuit (the one you get in your radio)
the reason a resistor is used is to limit current draw of the coil, because a low amp circuit can be easily switched by the ignitor in the distributor as compared to a high amp circuit (without resistor)..
you need to hookup that capacitor too - it helps in killing stray voltage spikes and also protects the ignitor from failing (on a khyber with electronic ignition its usually connected to a positive and a negative) and its usually a 0.47 uf bipolar capacitor (I connect these to radiator fan circuits too (helps in protecting the relay contacts and stray noises also)