How do you apply a jquery function with the function name as a parameter?

If you have a variable number of jQuery plugins of the format:

(function($){
    $.fn.toolSet_themeOne = function () {
        // params
    };
})(jQuery);


(function($){
    $.fn.toolSet_themeTwo = function () {
        // params
    };
})(jQuery);

Where each plugin's definition is not guaranteed to be the same and is likely to contain some degree of variation in name after the underscore, h开发者_高级运维ow could these be applied in a situation such as this:

var themeApply = function (jQueryCollection, objSettings, pluginName) {
    // this does not work and reports pluginName is not a function
    jQueryCollection.pluginName(objSettings);
    // $.fn[pluginName] is reported as a function
};

I thought to use another question as a guide, but don't see how to scope it correctly. Any pointers would be greatly appreciated.

Thank you :)

EDIT: For those wondering what function is inside, this is an example (learned from another SO answer for which I cannot find an immediate refrence:

(function($){

    $.fn.toolSet_themeOne = function () {

        var methods = [
            update: update
        ];

        var init = function (options) {
            // normal jquery initialisation here
        };

        var update = function (data) {
            // do something with data
            // if not initialising, but calling after initialisation
        };

        // what do we do on initialisation?
        if(arguments.length > 0) {
    if('string' === typeof(arguments[0]) && 'undefined' !== typeof(methods[arguments[0]])) {
        var args = Array.prototype.slice.call(arguments);  
        args = args.shift();
        methods[arguments[0]].apply(this,args);
    } else if('object' === typeof(arguments[0])) {
        init.apply(this, arguments);
    }
    } else {
    init.apply(this, arguments);
    }
    return this;
    };
})(jQuery);

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Does jQueryCollection[pluginName](objSettings) not work?