"The germs of love" is representative of metonymy in the above quotation from Jane Eyre by Charlotte Bronte. The conflict and intensity of feeling as Jane "wrought hard to extirpate from my soul... " is a recognizable consequence of loving someone so much; love often bringing with it unpleasant results. Metonymy often makes use of already understood and easily recognizable sequences (such as the effects of intense love) . The connection is indirect but very real and makes the argument for the negative effects of loving someone to the point that "the germs of love...spontaneously revived, green and strong." The vivid image is left with the reader who has no doubt about Jane's struggle with her feelings.
The bad weather, as reflected in Jane Eyre, is another example and is symbolic of a far bigger circumstance and often used to foreshadow events to follow. The reader understands this right from the beginning; "the cold winter wind had brought with it clouds so sombre, and a rain so penetrating,..."