and significant discussions, partly in favour of, partly
against the distinction between these two cell forms. After surveying
the literature, we are forced to separate the megaloblasts from the
normoblasts, in the first place because of their subsequent histories,
and the peculiarities of their nuclei, and secondly because of clinical
observation.

[alpha]. =The fate of the nuclei.= For some time past two views, almost
diametrically opposed, have been in existence with regard to the nature
of the change of the nucleated to the non-nucleated erythrocytes. The
chief exponent of the one, Rindfleisch, taught that the nucleus of the
erythroblasts leaves the cell, which thereby becomes a complete
erythrocyte, whilst the nucleus itself, by the aid of the small remnant
of protoplasm which surrounds it, takes up new material from the
surrounding plasma, manufactures haemoglobin and so becomes a fresh
erythroblast. According to the second theory the erythroblasts change
to non-nucleated discs by the destruction and solution of the nucleus
within the cell body. ("Karyorrhexis," "Karyolysis.") The authors who
support this view and also describe it as the only kind of erythrocyte
formation are chiefly Koelliker and E. Neumann.

Rindfleisch arrived at his theory by direct observation of the process
described, as it occurred in physiological saline solution with the
blood of foetal guinea-pigs and teased preparations of bone-marrow.

E. Neumann regards Rindfleisch's doctrine as untenable, since the
process which he observed is chiefly the result of a severe injury of
the blood from the sodium chloride solution and the teasing. If a method
of preparation be chosen which protects the blood as far as possible,
and avoids every chemical and physical alteration, the exit of the
nucleus as described by Rindfleisch does not occur.

The view of Koelliker and Neumann that the nuclei gradually decay in the
interior of the cell is not supported by the observation of a process,
but by the fact that in suitable material, for instance, foetal
bone-marrow, liver blood, and leukaemic blood, the transition from
erythroblast to erythrocyte is shewn by all phases of nuclear
metamorphosis. v. Recklinghausen professes to have directly observed the
dissolution of the nucleus within the cell in rabbit's blood, kept
living in a moist chamber. Pappenheim's opinion however, that in this
case processes are concerned such as Maragliano and Castellino have
d