I am reading The Great Gatsby, and came to be curious as to the meaning of "ramifications" and "by which" in these sentences:
Cody was fifty years old then, a product of the Nevada silver fields, of the Yukon, of every rush for metal since seventy-five. The transactions in Montana copper that made him many times a millionaire found him physically robust but on the verge of soft-mindedness, and, suspecting this, an infinite number of women tried to separate him from his money. The none too savory ramifications by which Ella Kaye, the newspaper woman, played Madame de Maintenon to his weakness and sent him to sea in a yacht, were common knowledge to the turgid sub-journalism of 1902. He had been coasting along all too hospitable shores for five years when he turned up as James Gatz's destiny in Little Girl Bay.
The narrator Nick is telling how Gatsby first came into being. Before he became Gatsby, he was named James Gatz; but when he met Dan Cody, who would start him in business and leave him inheritance, he decided to change his name to Jay Gatsby. When he met Gatsby, Dan Cody was soft-minded and was liable to be swayed by women.
In this part, I could not understand what "ramifications" and "by which" meant. Are the ramifications some flaws in his character derived from his soft-mindedness? Or the negative results, or rumors, caused by the fact that Ella Kaye pushed him out to the sea?
And I would also like to know what "by which" means. Does that mean Ella Kaye played Madame de Maintenon by the none too savory ramifications? If it is the case, what does "by" mean here? Did she use, or took the advantage of, the ramifications?
I would very much appreciate your help.