The way nature comes, in these forms of life, to her own aid in the case of injury, where the lack of one part necessary for the maintenance of the neighbouring parts is made good by the rest; the miscarriages or malformations in growth, where, on account of some chance defect or obstacle, certain parts adopt a completely new formation, so as to preserve the existing growth, and thus produce an anomalous form: these are matters which I only desire to mention here in passing, although they are among the most wonderful properties of the forms of organic life.