Below is the actual writing of Jack London: a much milder statement than the crude diatribe you attribute to a very esteemed author.


Despite being frequently attributed to London, the passage does not appear at all in the extensive collection of his writings at Sonoma State University's website. However, in his book The War of the Classes he published a 1903 speech entitled "The Scab",[72] which gave a much more balanced view of the topic:


To strike at a man's food and shelter is to strike at his life; and in a society organized on a tooth-and-nail basis, such an act, performed though it may be under the guise of generosity, is none the less menacing and terrible. It is for this reason that a laborer is so fiercely hostile to another laborer who offers to work for less pay or longer hours. To hold his place, (which is to live), he must offset this offer by another equally liberal, which is equivalent to giving away somewhat from the food and shelter he enjoys.
[...]
When a striker kills with a brick the man who has taken his place, he has no sense of wrong-doing. In the deepest holds of his being, though he does not reason the impulse, he has an ethical sanction. He feels dimly that he has justification, just as the home-defending Boer felt, though more sharply, with each bullet he fired at the invading English. Behind every brick thrown by a striker is the selfish will "to live" of himself, and the slightly altruistic will "to live" of his family. The family group came into the world before the State group, and society, being still on the primitive basis of tooth and nail, the will "to live" of the State is not so compelling to the striker as is the will "to live" of his family and himself.
[...]
The laborer who gives more time or strength or skill for the same wage than another, or equal time or strength or skill for a less wage, is a scab. The generousness on his part is hurtful to his fellow-laborers, for it compels them to an equal generousness which is not to their liking, and which gives them less of food and shelter. But a word may be said for the scab. Just as his act makes his rivals compulsorily generous, so do they, by fortune of birth and training, make compulsory his act of generousness.
[...]
Nobody desires to scab, to give most for least. The ambition of every individual is quite the opposite, to give least for most; and, as a result, living in a tooth-and-nail society, battle royal is waged by the ambitious individuals. But in its most salient aspect, that of the struggle over the division of the joint product, it is no longer a battle between individuals, but between groups of individuals. Capital and labor apply themselves to raw material, make something useful out of it, add to its value, and then proceed to quarrel over the division of the added value. Neither cares to give most for least. Each is intent on giving less than the other and on receiving more.