This clinical difference between the two kinds of haematoblasts admits of but one natural conclusion, which primarily leaves untouched the question, so much discussed at the present time, whether the megalo- or normoblasts can change one to the other. In all cases of anaemia, in which the fresh formation occurs according to the normal type, only in greater quantity and more energetically, we find normoblasts. Almost all anaemias resulting from known causes: acute haemorrhages, chronic haemorrhages, poverty of blood from inanition, cachexias, blood poisons, haemaglobinaemia and so forth,--in short all conditions rightly called, secondary, symptomatic anaemias,--may shew this increase of normal blood production. In the conditions, which Biermer, on the grounds of their clinical peculiarities, has distinguished as "essential, pernicious anaemia" megaloblasts on the contrary occur, and represent an embryonic type of development. The extent to which this type participates in the blood formation in pernicious anaemia is most simply demonstrated by the fact that megaloblasts are present in all cases of pernicious anaemia, as Laache first shewed, and in some cases form the preponderating portion of the blood discs. Whilst, therefore, in the ordinary kinds of anaemia we find that the red corpuscles tend to produce small forms, in pernicious anaemia, on the other hand, and exclusively in this form, we find a tendency in the opposite direction. This constant difference cannot be a chance result, but must depend on some constant law: in pernicious anaemia excessively large blood corpuscles are produced. Ehrlich's demonstration of megaloblasts has sufficed for this logical advance. =All researches, which try to obscure or totally deny the distinction between megaloblasts and normoblasts are wrecked by the simple clinical fact that in pernicious anaemia the blood is megaloblastic.=