The appearance of megaloblasts and megalocytes is therefore evidence that the regeneration of the blood in the bone-marrow is not proceeding in the normal manner, but in a way which approximates to the embryonic type. The extreme cases are naturally seldom, such as that of Rindfleisch, in which the whole bone-marrow was found full of megaloblasts. It is sufficiently conclusive for the pernicious nature of the case, "if only considerable portions but not the whole marrow, have lapsed into megaloblastic degeneration." We can now say that the megaloblastic metamorphosis is not a purposeful process, and for the following reasons: 1. Since the fresh formation of red blood corpuscles by means of the megaloblastic method is clearly much slower. This is especially borne out by the fact that the megaloblasts are present in the blood always in small numbers only, whilst the normoblasts, as above mentioned, are often found in much larger quantities. In agreement with this, "blood crises" are not to be observed in the megaloblastic anaemias. 2. Since the megalocytes which are formed from the megaloblasts possess in proportion to their volume a relatively smaller respiratory surface, and so constitute a type disadvantageous for anaemic conditions[10]. This is still more evident when we remember that the production of poikilocytes is on the contrary a serviceable process. The megaloblastic degeneration of the bone-marrow is no doubt due to chemical influences, which alter the type of regeneration in a disadvantageous manner. We do not for the most part yet know the exciting causes of the toxic process; consequently we are unable to put a stop to it, and its termination is lethal. The Bothriocephalus anaemias, which in general as is well-known offer a good prognosis, by no means contradict this view. They hold their privileged position amongst the anaemias of the megaloblastic type, only for the reason that their cause is known to us, and can be removed. As in many infectious diseases, individuals react quite differently to the presence of the Bothriocephalus. Some remain well; others show the signs of simple anaemia, ultimately with normoblasts; whilst a third group presents the typical picture of pernicious anaemia. For many years, so long as its aetiology was unknown, Bothriocephalus anaemia was not separated on clinical grounds from pernicious anaemia. Severe Bothriocephalus anaemia may be described as a pernicious anaemia, with a known and removable cause. Good evidence for this point of view is afforded by a case of Askanazy, who describes a severe pernicious anaemia, with typical megaloblasts, in which after the complete expulsion of the Bothriocephalus, the megaloblastic character of the blood formation quickly vanished, was replaced by the normoblastic, and the patient rapidly recovered. This observation is so unequivocal, that it is a matter of surprise that Askanazy chooses to deduce from it, the ready