"Usefull for some potions, including Shrinking Solution."

Rat spleens serve as a common potion ingredient. They can be used whole or liquefied. It is a required ingredient in the Shrinking Solution and in Dragon dung Fertiliser.[1]

In 1993, Neville Longbottom added too many rat spleens and too much leech juice into his Shrinking Solution, making it poisonous. Hermione Granger helped Neville fix the potion before Professor Snape had a chance to test it on Neville's toad, Trevor.[2]


Notes and references

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