"undeveloped figure" of the proletariat citations

I was reading Kautsky's Social Democracy vs. Communism. In part 9 he mentioned Marx using the term "'undeveloped figure' of the proletariat', explaining that, "...perceiving frequently in the capitalist who employs it not the exploiter who lives upon its labor but the master, the philanthropist, upon whose good will the wage earner subsists. Occasionally, these proletarians begin to glean vaguely the real character of the situation, which in turn, leads them to manifestations of resistance. But they are not capable of continuous, systematic struggle."

I can't find exact citations from Marx describing this, and I'm very interested in reading more about his thoughts on this particular type of proletarian, if someone happens to know where he talks about this, off the top of their head.